Method for displaying potential fingerprint traces and potential blood sweat mixed fingerprints

Abstract

The invention discloses a method for displaying a potential fingerprint trace and a method for displaying a potential blood-sweat mixed fingerprint. The method for displaying the potential fingerprint mark comprises the following steps: aligning a mist outlet of an atomizer filled with a crocein T solution to the surface of an object with the potential fingerprint mark for atomization; the object is a non-permeable object or a semi-permeable object. According to the method, pink fingerprint traces can be observed under natural light only by adopting the crocein T solution as a developing reagent through atomization treatment, fluorescence can be generated when a specific light source is further used for excitation, the fingerprint traces can be observed through an optical filter, the visible light and excitation dual modes are achieved, operation is easy and convenient, the developing time is extremely short, and the method is suitable for industrial production. Meanwhile, the method is suitable for latent sweating fingerprint marks and occult blood fingerprint marks. In addition, potential blood-sweat mixed fingerprints can be displayed by using the method provided by the invention.

Description

Technical Field

[0001] The invention relates to a method for revealing latent fingerprint traces and latent blood-sweat mixed fingerprints, and belongs to the field of fingerprint revealing in forensic science. Background Art

[0002] Fingerprint inspection technology is one of the key technologies for biological individual identification. Fingerprints left at the crime scene are often latent and cannot be identified by the naked eye. Physical, chemical or biological methods are needed to reveal fingerprints. Fingerprints at the crime scene include latent fingerprints on non-permeable, semi-permeable and permeable objects. At the same time, fingerprints can be divided into sweat latent, blood latent and oil-sweat mixed fingerprints according to the material composition. This also determines the diversity of methods for revealing latent fingerprints. At present, powder brushing, "502" glue revealing and vacuum coating are usually selected for sweat latent fingerprints on non-permeable objects. Powder brushing is a method of revealing fingerprints by using the principle of physical adhesion or electrostatic adsorption between fingerprint materials and powders. According to the physical properties of powders, they are classified into: ordinary powders (such as aluminum powders, bronze powders), fluorescent powders (such as anthracene powders), magnetic powders and plant powders, but this method is mainly suitable for relatively smooth and non-sticky samples. "502" glue is a colorless and transparent liquid that is easy to volatilize and polymerize into a solid. It is a commonly used adhesive. Its main component is α-cyanoacrylate ethyl. It can be induced to polymerize under the initiation of trace amounts of water, weak bases and other anions to form solid polymers, thereby revealing fingerprints. "502" glue fumigation is a commonly used method for revealing latent fingerprints on the surface of dark non-permeable objects, but the effect is not ideal for non-permeable objects with light backgrounds. Due to the weak contrast between the fingerprint lines and the background, optical and chemical staining methods are required for further processing. The operation is cumbersome and the types of reagents used are relatively large. Vacuum coating development method is used to reveal latent fingerprints on the surfaces of most non-permeable objects, including some objects after "502" glue fumigation. Under the vacuum environment conditions required for coating fingerprints, the coating material is heated and vaporized and coated on the surface of the object. Due to the different deposition effects of the coating material on the surface of the object with fingerprints and without fingerprints, a contrast is formed, thereby revealing the fingerprints. This method requires certain instruments and equipment, and can only be performed in the laboratory after the object with the fingerprint is extracted. For non-permeable objects, the development methods such as tetramethylbenzidine and acid yellow are usually selected. The tetramethylbenzidine development method is for light-colored non-permeable objects, and the development is achieved by smearing the fingerprint object. The acid yellow development method realizes the development of blood fingerprints through fixation, dyeing, rinsing and other steps. It can be seen that the existing methods are only for a certain type of fingerprint and a certain type of object, which also leads to the diversity of latent fingerprint methods. Although they can all show the fingerprint material to a certain extent, there are many defects such as cumbersome operation and long development time.

[0003] In addition, in the actual physical evidence inspection and identification, there are many incomplete latent blood fingerprints, which belong to latent blood and sweat mixed fingerprints. The latent blood and sweat mixed fingerprints refer to fingerprints that contain both blood components and sweat components. Specifically, from the perspective of material composition, the components of the latent blood part are mainly blood plus a small amount of sweat, and the components of the latent sweat part are mainly sweat components; from the perspective of the area of ​​the entire fingerprint, the latent blood area is the latent blood fingerprint, and the area outside the latent blood area is the latent sweat fingerprint. Under normal circumstances, after the latent blood and sweat mixed fingerprints are processed by the latent blood fingerprint display method, the latent blood fingerprints that appear are often small in effective area and have few feature points. At this time, if the latent sweat fingerprints connected to the latent blood area are processed by the latent sweat fingerprint display method, the display effect of the latent blood part will be affected, and it will be difficult to use for subsequent fingerprint inspection and identification. Therefore, the display of the latent blood and sweat mixed fingerprints is particularly important and is a difficulty in fingerprint display. In the prior art, the method for revealing latent blood fingerprints is only for fingerprints with latent blood components, and the method for revealing latent sweat fingerprints is only for fingerprints with latent sweat components, and it is impossible to completely and clearly reveal fingerprints mixed with latent blood and sweat.

[0004] Safranine T is a cationic dye, mainly used in the field of biological staining. When dissolved in ethanol, it exhibits red with yellow fluorescence. As a fluorescent dye, it has good fluorescence quantum yield and photostability. It is usually used as a laser medium and fluorescent tracer. There is no report on the appearance of safranine T in fingerprints. Summary of the invention

[0005] The purpose of the present invention is to provide a method for revealing latent fingerprint traces and latent blood-sweat mixed fingerprints. The method only uses Zanhong T solution as a revealing reagent. Pink fingerprint traces can be observed under natural light through atomization treatment. When further excited by a specific light source, fluorescence can be generated. The fingerprint traces can be revealed by observing with a filter and the revealing effect is good. The method of the present invention only uses one revealing reagent with simple components. During operation, only an atomizer is needed to atomize the surface of an object and excite it under a specific light source. The operation is simple and the revealing time is extremely short. The method has the characteristics of revealing fingerprints of multiple substances in one body, that is, it is suitable for latent sweat traces and latent blood traces at the same time. In addition, the method can also be used for latent blood-sweat mixed fingerprints to achieve complete revealing.

[0006] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for revealing latent fingerprint traces, comprising the following steps: Aim the atomizer outlet containing Zanhong T solution at the surface of the object with potential fingerprints to atomize; The guest is an impermeable guest or a semi-permeable guest.

[0007] In the above-mentioned method for revealing latent fingerprint traces, the solvent of the Zanghong T solution is anhydrous ethanol; The concentration of the Zanhong T solution is 0.5-3 g / L.

[0008] In the above-mentioned method for revealing latent fingerprint traces, the atomizer includes any one of an ultrasonic atomizer, a compression atomizer and a mesh atomizer; The specifications of the atomizer are as follows: the diameter of the droplets is 1 to 100 μm; preferably, the proportion of the mist particles with a diameter of 1 to 5 μm is greater than 50%, and the median particle size of the mist particles is 3±25% μm; The spray rate of the atomizer is 0.15 to 0.90 mL / min; In the atomization step, the distance between the atomization outlet and the object is 3 cm to 10 cm, and the atomization time is 3 to 10 seconds; The atomization is carried out in an environment with a temperature of 5-40° C. and a relative humidity of less than 80%.

[0009] In the above-mentioned method for revealing latent fingerprint traces, the method further comprises exciting with a light source to generate fluorescence after atomization is completed.

[0010] Furthermore, the latent fingerprint trace is observed under a filter, and the light source and filter used are any of the following: 1) The wavelength of the light source is 530nm, and the wavelength of the filter is 571nm; 2) The wavelength of the light source is 450nm and the wavelength of the filter is 571nm; 3) The wavelength of the light source is 450nm and the wavelength of the filter is 476nm.

[0011] In the above-mentioned method for revealing latent fingerprint traces, the latent fingerprint traces are latent blood traces or latent sweat traces; The handprint is a finger print or a palm print.

[0012] In a second aspect, the present invention provides a method for revealing latent blood-sweat mixed handprints, comprising the following steps: Aim the atomizer outlet filled with Zanghong T solution at the surface of the object with the incomplete blood fingerprint to atomize; The guest is an impermeable guest or a semi-permeable guest.

[0013] In the above-mentioned method for revealing latent blood-sweat mixed fingerprints, the solvent of the Zanghong T solution is anhydrous ethanol; The concentration of the Zanhong T solution is 0.5-3 g / L.

[0014] In the above-mentioned method for revealing latent blood-sweat mixed handprints, the atomizer includes any one of an ultrasonic atomizer, a compression atomizer and a mesh atomizer; The specifications of the atomizer are as follows: the diameter of the droplets is 1 to 100 μm; preferably, the proportion of the mist particles with a diameter of 1 to 5 μm is greater than 50%, and the median particle size of the mist particles is 3±25% μm; The spray rate in the atomization step is 0.15 to 0.90 mL / min; In the atomization step, the distance between the atomization outlet and the object is 3 cm to 10 cm, and the atomization time is 3 to 10 seconds; The atomization is carried out in an environment with a temperature of 5-40° C. and a relative humidity of less than 80%.

[0015] In the above-mentioned method for revealing latent blood-sweat mixed handprints, the method further comprises exciting with a light source to generate fluorescence after atomization is completed; The mutilated bloody handprint is observed under a filter, and the light source and filter used are any of the following: 1) The wavelength of the light source is 530nm, and the wavelength of the filter is 571nm; 2) The wavelength of the light source is 450nm and the wavelength of the filter is 571nm; 3) The wavelength of the light source is 450nm and the wavelength of the filter is 476nm.

[0016] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The present invention uses an ethanol solution of Zanghong T as a developing reagent, has a small number of components, stable solvent properties, simple preparation, and is safe and environmentally friendly.

[0017] (2) Atomization technology is to turn the reagent into fine droplets. The principle is to use high-frequency electronic oscillation and high-frequency resonance of the atomizer to break up the liquid molecular structure or pass the solution through the metal mesh to produce a natural and elegant mist, without heating or adding any chemical reagents. The present invention directly uses atomization technology to atomize the Zanghong T solution into droplets, which are fully contacted and reacted with the fingerprint material. The fingerprint traces can be directly revealed by direct reaction under room temperature conditions. No additional reagents and conditions are required, the operation is simple, and the required visualization time can be greatly shortened.

[0018] (3) After the latent fingerprint object is processed by the present invention, pink lines can be observed by naked eyes under visible light. Further, fluorescent fingerprints can be visualized under the stimulation of a specific light source. When observed under a filter, the fluorescence brightness is strong, the lines are clear, and the overall visualization effect is good.

[0019] (4) The method of the present invention is not only applicable to latent sweat fingerprints, but also to latent blood fingerprints, and has a good revealing effect on latent blood and sweat mixed fingerprints. (5) The method of the present invention is not only applicable to non-permeable objects, but also to semi-permeable objects (such as leather), and can be applied to a wider range of objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 (A) is a diagram showing the effect of a latent blood fingerprint observed under different wavelength excitations and different filters in Example 1 of the present invention.

[0021] FIG1 (B) is a diagram showing the effect of latent sweat fingerprints observed under different wavelength excitations and different filters in Example 1 of the present invention.

[0022] FIG2 (A) is a diagram showing the effects of latent sweat fingerprints observed with the naked eye under different treatment methods (micro-grid atomization, spraying, smearing and dripping) in Example 2 of the present invention.

[0023] FIG2 (B) is a diagram showing the effect of latent sweat fingerprints under different treatment methods (micro-grid atomization, spraying, smearing and dripping) in Example 2 of the present invention, excited by a 530 nm light source and observed with a 571 nm filter.

[0024] FIG2 (C) is a diagram showing the effects of latent blood fingerprints observed with the naked eye under different treatment methods (micro-mesh atomization, spraying, smearing and dripping) in Example 2 of the present invention.

[0025] FIG2 (D) is a diagram showing the effect of a latent blood fingerprint observed with a 571 nm filter under different treatment methods (micro-grid atomization, spraying, smearing and dripping) in Example 2 of the present invention using a 530 nm light source for excitation.

[0026] Figure 3 This is a diagram showing the effect of latent sweat fingerprints on an enamel plate in Example 3 of the present invention, wherein: Figure 3 The above is a photo of the enamel plate with fingerprints before micro-grid atomization treatment with Zanghong T. Figure 3 The middle is a photo of the enamel plate with fingerprints observed by naked eyes after micro-grid atomization treatment with Zanghong T. Figure 3 The following is a photograph of an enamel plate with fingerprints printed on it, which was treated with Zanghong T through micro-grid atomization and then excited with a 530nm light source and observed with a 571nm filter.

[0027] Figure 4 This is a diagram showing the effect of latent sweat fingerprints on a plastic culture dish in Example 4 of the present invention, wherein: Figure 4 The left picture shows the plastic petri dish with fingerprints after micro-grid atomization with Zanghong T and observed with naked eyes. Figure 4 On the right is a photograph of a plastic petri dish with fingerprints printed on it, which was treated with Zanghong T through micro-mesh atomization and then excited with a 530nm light source and observed with a 571nm filter.

[0028] Figure 5 This is a diagram showing the effect of latent blood fingerprints on a colorless transparent plastic bag in Example 5 of the present invention, wherein: Figure 5 The above is a photo of a latent blood fingerprint on a colorless transparent plastic bag before it was exposed. Figure 5 The middle is a photo of a latent blood fingerprint under white light after micro-grid atomization. Figure 5 The following is a photograph of a colorless transparent plastic bag with fingerprints printed on it, which was treated with Zanghong T through a micro-mesh atomization, then excited with a 530nm light source and observed with a 571nm filter.

[0029] Figure 6 This is a diagram showing the effect of latent blood fingerprints on a black plastic bag in Example 6 of the present invention, wherein: Figure 6 The left photo shows the latent blood fingerprint on the black plastic bag before it is exposed. Figure 6 On the right is a photograph of a fingerprint on a black plastic bag that was treated with Zanghong T through a micro-mesh atomization, then excited with a 530nm light source and observed with a 571nm filter.

[0030] Figure 7 This is a diagram showing the effect of latent blood fingerprints on white leather in Example 7 of the present invention. Figure 7 The left photo shows a latent blood handprint on white leather before it was exposed. Figure 7 The middle is a photo of latent blood fingerprints on white leather after micro-mesh atomization under natural light conditions. Figure 7 On the right is a photograph of white leather with fingerprints printed on it, which was treated with Zanghong T through micro-mesh atomization, then excited with a 530nm light source and observed with a 571nm filter.

[0031] Figure 8 This is a diagram showing the effect of latent sweat fingerprints on white leather in Example 8 of the present invention. Figure 8 The left photo shows a latent sweat handprint on white leather before it was exposed. Figure 8 The middle is a photo of latent sweat fingerprints on white leather after micro-mesh atomization treatment under natural light conditions. Figure 8 On the right is a photograph of white leather with fingerprints printed on it, which was treated with Zanghong T through micro-mesh atomization, then excited with a 530nm light source and observed with a 571nm filter.

[0032] Fig. 9 This is a repair effect diagram of latent blood fingerprints on aluminum foil in Example 9 of the present invention, wherein: Fig. 9 The left is a photo of the latent blood fingerprint before it was processed. Fig. 9 The middle is a photo of a latent blood fingerprint observed with the naked eye after micro-net atomization treatment. Fig. 9 On the right is a photograph of a latent blood handprint observed with a 530nm light source and a 571nm filter.

[0033] Fig.10 This is a repair effect diagram of the latent blood, sweat and handprint on the white plastic bag in Example 10 of the present invention, wherein: Fig.10 The left is a photo of the latent blood, sweat and handprints before processing. Fig.10 The middle is a photo of potential mixed blood and sweat fingerprints observed by naked eyes after micro-grid atomization treatment. Fig.10 On the right is a photograph of a latent blood and sweat mixed handprint observed with a 530nm light source and a 571nm filter.

[0034] Fig.11 This is a rendering of the latent blood, sweat and handprint on white leather in Example 11 of the present invention, wherein: Fig.11 The left is a photo of the latent blood, sweat and handprints before processing. Fig.11 The middle is a photo of potential blood and sweat mixed fingerprints observed by naked eyes after micro-grid atomization treatment. Fig.11 On the right is a photograph of a latent blood and sweat mixed handprint observed with a 530nm light source and a 571nm filter. DETAILED DESCRIPTION

[0035] As described in the background art, currently, for non-permeable objects, sweat latent handprints are usually revealed by powder brushing, "502" glue, vacuum coating and other methods. These methods are only for a certain type of handprint, a certain type of object, cumbersome operation, and long revealing time. However, the inventor unexpectedly discovered in practice that by using Zanghong T alone to atomize and reveal handprint traces, pink lines can be directly observed under visible light (the contrast effect is more obvious on light-colored non-permeable objects).

[0036] Based on this, in the first part, the present invention provides a method for revealing latent fingerprints, comprising the following steps: aiming the mist outlet of an atomizer filled with Zanhong T solution at the surface of an object of the latent fingerprint for atomization; the object is a non-permeable object or a semi-permeable object. The method of the present invention not only solves the problem that the current revealing method is applicable to a single fingerprint and object to a large extent, but also avoids the problems of cumbersome operation and long revealing time existing in the current color development method, and is applicable to latent blood fingerprints and latent sweat fingerprints, non-permeable objects and semi-permeable objects at the same time. In addition, the fingerprint imaging has a dual mode of visible light and excitation.

[0037] In the embodiment of the present invention, the inventors compared the effects of different operation methods such as micro-grid atomization, spraying, smearing, and dripping on the appearance of handprint traces. The results showed that only by using micro-grid atomization can clear and complete lines be obtained. This may be because the micro-grid atomization technology can change the liquid Zang Hong T solution into a fine mist, and the fine mist Zang Hong T solution can be evenly adsorbed on the handprint line material, which is visible to the naked eye and can stimulate fluorescence. Among them, as an example, the solvent of the Zang Hong T solution is anhydrous ethanol; the concentration of the Zang Hong T solution is 1.5 to 3 g / L, such as 1.5g / L.

[0038] According to the present invention, unlike a spray pot (the diameter of the droplets is about several hundred microns or even larger), the atomizer can atomize the solution into micron-sized aerosol particles. In the present invention, the atomizer includes any one of an ultrasonic atomizer, a compression atomizer and a mesh atomizer. The mesh atomizer can be a device that uses high-frequency resonant oscillation to atomize the solution into micron-sized particles through a mesh. Optionally, it can be driven by a certain frequency oscillation of the circuit to make the piezoelectric ceramic transducer resonate and oscillate, thereby driving the metal mesh to oscillate at high speed, so that the solution passes through many tiny mesh holes on the metal mesh and is quickly ejected to form countless tiny atomized particles. Further, the specifications of the atomizer are as follows: the droplet diameter is 1 to 100 μm; preferably, the proportion of fog particles with a diameter of 1 to 5 μm is greater than 50%, and the median particle size of the fog particles is 3 ± 25% μm; wherein, the median particle size of the fog particles is measured with 0.9% saline at a temperature of 2 ° C and a humidity of 59%. And the equivalent volume particle size distribution curve of the mist particles measured under this condition is used to obtain the proportion of droplets with a diameter of 1 to 5 μm. The atomization rate of the atomizer is 0.15 to 0.90 mL / min, such as the intermediate speed. Regarding the atomization time, the atomization reagent is fully contacted with the fingerprint material during the treatment process, which can usually be completed in several seconds, such as 3 to 10 seconds. The distance between the mist outlet and the object can be appropriately adjusted within 3 cm to 10 cm. In an embodiment of the present invention, the atomizer is a medical atomizer, such as a mesh atomizer (micromesh atomizer) with an oscillation frequency of 130 KHz ± 10%. As an example, the microporous micromesh atomizer Air Plus 2 of Jiuan Medical is used. When in use, aim the mist outlet of the micromesh atomizer at the object with potential fingerprint traces, and start the micromesh atomizer for atomization.

[0039] According to the present invention, in the present invention, the object can be an impermeable object or a semi-permeable object. The object is distinguished according to its ability to absorb liquid. The impermeable object includes but is not limited to enamel, stainless steel, plastic, aluminum foil and other objects that do not absorb liquid, such as white plastic bags, transparent plastic bags or black plastic bags; the semi-permeable object includes but is not limited to leather, such as white leather.

[0040] According to the present invention, the atomization is carried out in an environment with a temperature of 5 to 40°C and a relative humidity of <80%. In the present invention, the term "relative humidity" is represented by RH (Relative Humidity), which refers to the ratio of the actual water vapor pressure in the air to the saturated water vapor pressure at the current temperature. It reflects the degree of air away from saturated air and represents the ratio of the absolute humidity in the air to the saturated absolute humidity at the same temperature and pressure. It is a percentage value, that is, it refers to the mass ratio of water vapor contained in a certain wet air to the mass ratio of water vapor contained in saturated air at the same temperature and pressure. During the operation, those skilled in the art can determine it according to the environment (geographic location, season) in which the experiment is located. For example, in the embodiment of the present invention, the temperature is 24°C and the relative humidity is 40%, but the present invention is by no means limited to this, as long as the appropriate conditions are met to enable the atomized reagent to be adsorbed on the grain line.

[0041] Further preferably, the method further comprises exciting with a light source to produce fluorescence after atomization is completed. Specifically, it can be selected whether to further use a specific light source to excite and produce fluorescence as needed. For example, sweat or blood latent fingerprints on the surface of a light-colored object can be directly observed with the naked eye, and the fluorescence produced by combining the excitation light source can further enhance the display effect. Among them, the wavelength of the light source is determined according to the fluorescence excitation wavelength of Zanghong T. The latent fingerprint traces can be specifically observed under a filter, and the filter can be determined according to the fluorescence color. In the embodiments of the present invention, the inventors tried a variety of excitation wavelengths and fluorescent film wavelengths, and found that the display effect is better in any of the following limit: 1) the wavelength of the light source is 530nm, and the wavelength of the filter is 571nm; 2) the wavelength of the light source is 450nm, and the wavelength of the filter is 571nm; 3) the wavelength of the light source is 45nm 0, and the wavelength of the filter is 476nm.

[0042] According to the present invention, the latent handprint traces may be latent blood traces or latent sweat traces, the latent blood traces are latent blood handprints (blood latent handprints), and the latent sweat traces are latent sweat handprints (sweat latent handprints). The handprints may be finger prints or palm prints. Based on the same technical principle, when the latent handprint traces are mixed blood and sweat handprint traces, the method of the present invention can simultaneously display the latent blood and sweat mixed handprints.

[0043] Based on this, in the second part, the present invention provides a method for revealing latent blood-sweat mixed fingerprints, comprising the following steps: aiming the mist outlet of an atomizer filled with Zanghong T solution at the surface of the object of the latent blood-sweat mixed fingerprints for atomization; the object is a non-permeable object or a semi-permeable object. Among them, the latent blood-sweat mixed fingerprints refer to a part of the area being a latent blood fingerprint or blood palm print, and a part of the area being a sweat latent fingerprint or palm print. The blood-sweat mixed fingerprints are revealed by the method of the present invention, which can display the complete latent blood-sweat mixed fingerprints on the one hand, and further enhance the color of the fingerprints on the other hand.

[0044] In the present invention, unless otherwise specified, relevant terms may refer to the relevant definitions in standards such as "GA / T144-2018 Forensic Science Fingerprint Professional Terminology".

[0045] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0046] The methods used in the following examples, unless otherwise specified, are all conventional methods, carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0047] The sources of the materials in the following examples are as follows: Safflower T (AR, 85%, MW: 350.85), Aladdin; Ethanol (absolute ethanol) (analytical grade, AR, C 2 H 6 O, FW 46.07), Shanghai test.

[0048] The sources of the instruments in the following embodiments are as follows: Atomizer (Air Plus 2 Jiuan), the particle size is 0.1-10μm, the proportion of 1-5μm particles is greater than 50%, the median particle size is 3±25%μm, the spray rate is 0.15-0.90mL / min (default gear - medium speed), and the operating frequency is 130KHz±10%.

[0049] The equipment for taking photos and observing is a multi-band light source (PL500, ROFIN, Australia).

[0050] Example 1: Comparison of fingerprint visualization using different wavelength light sources and different filters Latent blood fingerprint: Use anhydrous ethanol as solvent to prepare 1.5g / L Safranin T solution. With black plastic bags as the object, according to the simulated on-site environment, the volunteers' hands were not treated in any way. Under natural conditions, blood (human blood, 100% concentration) was dipped with absorbent cotton and smeared on the fingers. After smearing evenly, handprints (fingerprints) were directly made and placed for 10 months at a temperature of 24°C and a relative humidity of 30%. Then the atomizer containing the safranin T solution was aimed at the surface of the object for atomization. The distance between the mist outlet and the object was 5 cm. After atomization for 3 seconds, the light sources with wavelengths of 415nm, 450nm, 470nm, 490nm, 505nm, 530nm, 555nm and 590nm were used for excitation, and a red filter (571nm) was used for observation; the light sources with wavelengths of 415nm, 450nm, 470nm, 490nm and 505nm were used for excitation, and an orange filter (529nm) was used for observation; the light source with wavelengths of 415nm was used for excitation, and a yellow filter (476nm) was used for observation. The results are shown in Figure 1 (A). When a 530nm light source is selected for excitation and a red filter (571nm), the wavelength of the light source is 450nm and the wavelength of the filter is 571nm, or the wavelength of the light source is 450nm and the wavelength of the filter is 476nm, the best effect on the visualization of latent blood fingerprints is achieved.

[0051] Latent sweat handprint: Anhydrous ethanol was used as solvent to prepare 1.5g / L Safranin T solution. A white enamel plate was used as the object. According to the simulated on-site environment, the volunteers did not do any treatment on their hands and directly pressed handprints (fingerprints) under natural conditions and placed them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then the atomizer containing the Safranin T solution was aimed at the surface of the object for atomization. The distance between the atomization outlet and the object was 5cm. After atomization for 3s, it was immediately excited with light sources of wavelengths of 415nm, 450nm, 470nm, 490nm, 505nm, 530nm, 555nm and 590nm, and observed with a red filter (571nm); excited with light sources of wavelengths of 415nm, 450nm, 470nm, 490nm and 505nm, and observed with an orange filter (529nm); excited with a light source of 415nm, and observed with a yellow filter (476nm). The results are shown in Figure 1 (B). When a 530nm wavelength light source is selected for excitation and a red filter (571nm), the wavelength of the light source is 450nm and the wavelength of the filter is 571nm, or the wavelength of the light source is 450nm and the wavelength of the filter is 476nm, the best effect on the visualization of latent blood fingerprints is achieved.

[0052] Example 2: Comparison of fingerprint appearance under different treatment methods Latent sweat handprints: Anhydrous ethanol was used as the solvent to prepare a 1.5 g / L Safranin T solution. A white plastic bag was used as the object. According to the simulated on-site environment, the volunteers did not do any treatment on their hands. They directly pressed their handprints (fingerprints) under natural conditions and left them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, the above-mentioned Safranin T solution was used to treat the surface of the object by micro-net atomization, spraying, smearing and dripping. The results were observed with the naked eye and photographed. The results are shown in Figure 2 (A). Then, a 530 nm light source was used for excitation and a 571 nm filter was used for observation. Fluorescent handprints can be seen. After taking pictures and observing, the results are shown in Figure 2 (B).

[0053] Latent blood fingerprint: Anhydrous ethanol was used as solvent to prepare 1.5g / L of Safranin T solution. A white plastic bag was used as the object. According to the simulated on-site environment, the volunteers did not do any treatment on their hands. Under natural conditions, blood (human blood, 100% concentration) was dipped into absorbent cotton and smeared on the fingers. After smearing evenly, the fingerprints were directly pressed and placed for 10 months at a temperature of 24°C and a relative humidity of 30%. Then, the surface of the object was treated with the above-mentioned Safranin T solution by micro-net atomization, spraying, smearing and dripping, respectively. The results were observed with the naked eye and photographed. The results are shown in Figure 2 (C). Then, it was excited with a 530nm light source and observed with a 571nm filter. Fluorescent fingerprints can be seen. After taking pictures and observing, the results are shown in Figure 2 (D).

[0054] The specific operations of each processing method are as follows: Micro-grid atomization: Aim the atomizer filled with Safranin T solution at the surface of the object for atomization, the distance between the atomization outlet and the object is 5 cm, and the atomization time is 3 s; Spraying: Use a spray bottle filled with Safranin T solution to spray on the surface of the object for 10 seconds; Apply: Apply the cotton ball with Safranin T solution on the surface of the handprint object until it reaches the surface of the handprint object; Dripping: Use a rubber-tipped dropper to drop one or two drops of Safranin T solution on the area where the fingerprint may exist until the solution covers the entire fingerprint, and use absorbent paper to remove excess developer from the edge of the object.

[0055] It can be seen from FIG. 2 (A) to FIG. 2 (D) that, compared with other treatment methods, whether for sweat latent fingerprints or blood latent fingerprints, the micro-grid atomization treatment of the present invention can observe clear and complete fingerprint lines with the naked eye under natural light, while the background is clean and free of other interferences, and the fluorescent fingerprint observed under 530nm light source excitation and 571nm filter has the best visualization effect.

[0056] Example 3: Latent sweat fingerprints appear on enamel plates With anhydrous ethanol as solvent, 1.5 g / L of Safranin T solution was prepared. Ordinary stainless steel was used as the object. According to the simulated on-site environment, volunteers' hands were not treated in any way and were directly printed with handprints (fingerprints) under natural conditions. Figure 3 The object was placed on the surface of the object and placed for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then the atomizer containing the safranin T solution was directed to the surface of the object for atomization. The distance between the atomization outlet and the object was 5 cm. After atomization for 3 seconds, the pink color contrast was visible to the naked eye. Figure 3 Then use 530nm light source to excite and 571nm filter to observe, and the fluorescent handprint can be seen. Figure 3 As shown below.

[0057] Example 4: Display of latent sweat fingerprints on plastic culture dishes With anhydrous ethanol as solvent, 1.5g / L Safranin T solution was prepared. With plastic petri dishes as objects, according to the simulated on-site environment, volunteers did not do any treatment on their hands, and directly pressed handprints (fingerprints) under natural conditions, and left them for 5 hours at a temperature of 24°C and a relative humidity of 20%. Then, the atomizer containing the Safranin T solution was aimed at the surface of the object for atomization, and the distance between the atomization port and the object was 5cm. After atomization for 3s, a light pink contrast was visible to the naked eye. Figure 4 Left, then use 530nm light source to excite, 571nm filter to observe, you can see the fluorescent handprint. After taking pictures and observing, the results are as follows Figure 4 Shown right.

[0058] Example 5: Latent blood fingerprints appear on plastic bags Use anhydrous ethanol as solvent to prepare 1.5g / L Safranin T solution. Use ordinary colorless transparent plastic bag as object, see Figure 5 In the simulation of the on-site environment, volunteers did not do any treatment on their hands. Under natural conditions, blood (human blood, 100% concentration) was dipped into absorbent cotton and smeared on their fingers. After smearing evenly, handprints (fingerprints) were directly made and placed for 10 months at a temperature of 24°C and a relative humidity of 30%. Figure 5 Then, the atomizer containing the safranin T solution was directed to the surface of the object for atomization. The distance between the atomizer outlet and the object was 5 cm. After atomization for 3 seconds, obvious pink lines were visible to the naked eye. Then, a 530nm light source was used for excitation and a 571nm filter was used for observation, and fluorescent handprints were visible. After taking pictures and observing, the results were as follows: Figure 5 As shown below.

[0059] Example 6: Latent blood fingerprints appear on black plastic bags With anhydrous ethanol as solvent, a 1.5 g / L solution of Safranin T was prepared. With ordinary black plastic bags as the object, according to the simulated field environment, volunteers did not do any treatment on their hands. Under natural conditions, blood (human blood, 100% concentration) was dipped in absorbent cotton and smeared on their fingers. After smearing evenly, handprints (fingerprints) were directly made and placed for 10 months at a temperature of 24°C and a relative humidity of 30%. Figure 6 Left, then the above-mentioned atomizer containing the Safranin T solution is aimed at the surface of the object for atomization, and the distance between the atomization port and the object is 5 cm. After atomization for 3 seconds, it is immediately excited with a 530nm light source and observed with a 571nm filter, and the fluorescent handprint can be seen. After taking pictures and observing, the results are as follows Figure 6 Shown right.

[0060] Example 7: Visualization of latent blood fingerprints on white leather With anhydrous ethanol as solvent, 1.5 g / L of Safranin T solution was prepared. With white leather as the object, according to the simulated field environment, volunteers did not do any treatment on their hands. Under natural conditions, blood (human blood, 100% concentration) was dipped in absorbent cotton and smeared on the fingers. After smearing evenly, handprints (fingerprints) were directly made and placed for 3 days at a temperature of 24°C and a relative humidity of 30%. Figure 7 The atomizer containing the safranin T solution was then directed to the surface of the object for atomization. The distance between the atomizer outlet and the object was 3 cm. After atomization for 5 seconds, pink lines were visible to the naked eye. Figure 7 Then, it was excited with a 530nm light source and observed with a 571nm filter, and the fluorescent handprints could be seen. Figure 7 Shown right.

[0061] Example 8: Display of latent sweat fingerprints on white leather With anhydrous ethanol as solvent, a 1.5 g / L solution of Safranin T was prepared. With white leather as the object, according to the simulated field environment, volunteers' hands were not treated in any way, and handprints (fingerprints) were directly made under natural conditions and left for 5 hours at a temperature of 24°C and a relative humidity of 30%. Figure 8 Left, then the above-mentioned atomizer containing the safranin T solution was directed to the surface of the object for atomization, and the distance between the atomization port and the object was 3 cm. After atomization for 5 seconds, light pink lines were visible to the naked eye. Figure 8 Then, it was excited with a 530nm light source and observed with a 571nm filter, and the fluorescent handprints could be seen. Figure 8 Shown right.

[0062] Example 9: Latent blood fingerprints on aluminum foil packaging bags Using anhydrous ethanol as solvent, a 1.5 g / L solution of Safranin T was prepared. Using an aluminum foil bag as the object, according to the simulated field environment, volunteers did not do any treatment on their hands. Under natural conditions, blood (human blood, 100% concentration) was dipped in absorbent cotton and smeared on their fingers. After smearing evenly, handprints (fingerprints) were directly made and placed for 3 days at a temperature of 24°C and a relative humidity of 30%. Fig. 9 The latent blood fingerprint on the aluminum foil packaging bag shown on the left is revealed: the above-mentioned atomizer containing the safranin T solution is directed to the surface of the object for atomization. After atomization for 3 seconds, as shown in FIG. Fig. 9 As shown in the figure, the fingerprint lines are visibly darker and almost complete. Then, the fingerprint lines are excited with a 530nm light source and observed with a 571nm filter, and fluorescent fingerprints can be seen, as shown in the figure. Fig. 9 Shown right.

[0063] Example 10: Latent blood, sweat and fingerprints on white plastic bag revealed With anhydrous ethanol as solvent, 1.5g / L Safranin T solution was prepared. With white plastic bags as objects, according to the simulated on-site environment, volunteers did not do any treatment on their hands, and then used absorbent cotton to dip blood (human blood, 100% concentration) and smeared it on part of the finger (i.e. the position of the pattern from the center of the fingerprint to the fingertip) under natural conditions, and then the whole finger was directly pressed with a handprint (fingerprint), and left for 3 days to form a mixed blood and sweat handprint (the latent blood area (center to fingertip position area) is the latent blood handprint, and the area outside the latent blood area is the latent sweat handprint), the temperature is 24℃, the relative humidity is 30%, and the Fig.10 The blood and sweat mixed fingerprint on the white plastic bag shown on the left is visualized: the above-mentioned atomizer containing the safranin T solution is directed to the surface of the object for atomization. After atomization for 3 seconds, Fig.10 As shown in the figure, the fingerprint lines are visibly darker and some lines that were not visible before treatment are revealed. The effect is now further enhanced. Then, a 530nm light source is used for excitation and a 571nm filter is used for observation. Fig.10 As shown on the right, a fluorescent handprint with nearly complete lines can be observed. It can be seen that the method of the present invention can fully visualize the mixed blood and sweat handprint.

[0064] Example 11: Latent blood, sweat and handprints on white leather With anhydrous ethanol as solvent, 1.5g / L of Safranin T solution was prepared. With white leather as the object, according to the simulated field environment, volunteers did not do any treatment on their hands, and then used absorbent cotton to dip blood (human blood, 100% concentration) and smear it on part of the finger (i.e. the position area of ​​the pattern from the center of the fingerprint to the fingertip) under natural conditions, and then the whole finger was directly pressed with a handprint (fingerprint), and left for 3 days to form a mixed blood and sweat handprint (the latent blood area (center to fingertip position area) is the latent blood handprint, and the area outside the latent blood area is the latent sweat handprint), the temperature is 24℃, the relative humidity is 30%, and the Fig.11 The latent blood and sweat mixed handprint on the white leather shown on the left is revealed: the above-mentioned atomizer filled with Safranin T solution is directed to the surface of the object for atomization. After atomization for 5 seconds, as shown in FIG. Fig.11 As shown in the figure, the fingerprint lines are visibly darker and almost complete, and then excited with a 530nm light source and observed with a 571nm filter. Fig.11 As shown on the right, it can be seen that the method of the present invention can reveal the latent blood-sweat mixed handprint on white leather.

[0065] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, can implement the present invention in a wider range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principle of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departing from the disclosed scope in the application and the changes made with conventional techniques known in the art.

Claims

1. A method for revealing latent fingerprint traces, characterized in that: The steps include: Aim the atomizer outlet containing Zanhong T solution at the surface of the object with potential fingerprints to atomize; The guest is an impermeable guest or a semi-permeable guest.

2. The method for revealing latent fingerprint traces according to claim 1, characterized in that: The solvent of the Zanghong T solution is anhydrous ethanol; The concentration of the Zanhong T solution is 0.5-3 g / L.

3. The method for revealing latent fingerprint traces according to any one of claims 1-2, characterized in that: The nebulizer includes any one of an ultrasonic nebulizer, a compression nebulizer and a mesh nebulizer; The specifications of the atomizer are as follows: the diameter of the droplets is 1 to 100 μm; preferably, the proportion of the mist particles with a diameter of 1 to 5 μm is greater than 50%, and the median particle size of the mist particles is 3±25% μm; The spray rate of the atomizer is 0.15 to 0.90 mL / min; In the atomization step, the distance between the atomization outlet and the object is 3 cm to 10 cm, and the atomization time is 3 to 10 seconds; The atomization is carried out in an environment with a temperature of 5-40° C. and a relative humidity of less than 80%.

4. The method for revealing latent fingerprint traces according to any one of claims 1 to 3, characterized in that: The method further comprises exciting with a light source to generate fluorescence after atomization is completed.

5. The method for revealing latent fingerprint traces according to claim 4, characterized in that: The latent fingerprint traces are observed under a filter, and the light source and filter used are any of the following: 1) The wavelength of the light source is 530nm, and the wavelength of the filter is 571nm; 2) The wavelength of the light source is 450nm and the wavelength of the filter is 571nm; 3) The wavelength of the light source is 450nm and the wavelength of the filter is 476nm.

6. The method for displaying fingerprint traces according to any one of claims 1 to 5, characterized in that: The latent fingerprint traces are latent blood traces or latent sweat traces; The handprint is a finger print or a palm print.

7. A method for revealing latent blood-sweat mixed fingerprints, characterized in that: The steps include: Aim the atomizer outlet filled with Zanghong T solution at the object surface with potential blood-sweat mixed fingerprints to atomize; The guest is an impermeable guest or a semi-permeable guest.

8. The method for revealing latent blood-sweat mixed fingerprints according to claim 7, characterized in that: The solvent of the Zanghong T solution is anhydrous ethanol; The concentration of the Zanhong T solution is 0.5-3 g / L.

9. The method for revealing latent blood-sweat mixed fingerprints according to claim 7 or 8, characterized in that: The nebulizer includes any one of an ultrasonic nebulizer, a compression nebulizer and a mesh nebulizer; The specifications of the atomizer are as follows: the diameter of the droplets is 1 to 100 μm; preferably, the proportion of the mist particles with a diameter of 1 to 5 μm is greater than 50%, and the median particle size of the mist particles is 3±25% μm; The spray rate of the atomizer is 0.15 to 0.90 mL / min; In the atomization step, the distance between the atomization outlet and the object is 3 cm to 10 cm, and the atomization time is 3 to 10 seconds; The atomization is carried out in an environment with a temperature of 5-40° C. and a relative humidity of less than 80%.

10. The method for revealing latent blood-sweat mixed handprint according to any one of claims 7-9, characterized in that: The method further comprises exciting with a light source to generate fluorescence after atomization is completed; The mutilated bloody handprint is observed under a filter, and the light source and filter used are any of the following: 1) The wavelength of the light source is 530nm, and the wavelength of the filter is 571nm; 2) The wavelength of the light source is 450nm and the wavelength of the filter is 571nm; 3) The wavelength of the light source is 450nm and the wavelength of the filter is 476nm.

Images