Reagent appearance fingerprint temperature control method applied to paper

Abstract

The invention relates to the technical field of forensic science criminal affairs, in particular to the field of special laboratory trace inspection, and more particularly relates to a reagent appearance fingerprint temperature control method applied to paper. A reagent appearing fingerprint temperature control method applied to paper is characterized by comprising the following steps that S1, an experiment is conducted in the same experiment environment; s2, taking indandione as a fingerprint appearing reagent, and dividing the fingerprint appearing reagent into a group A; ninhydrin is used as a fingerprint development reagent and is divided into a group B; s3, respectively carrying out the group A experiment and the group B experiment, gradually raising the temperature to carry out a fingerprint showing experiment in a short time when the experiment setting requirement is met, and judging the fingerprint showing effect, and recording the optimal baking temperature interval and the corresponding time; and S4, aiming at an experiment result, when a fingerprint display effect picture is obtained, performing standard photographing on the fingerprint, so that under a normal observation distance, pixel points cannot be distinguished by naked eyes, and potential fingerprints can be completely displayed and are regarded as clear and complete.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of forensic science, in particular to the field of laboratory trace inspection, and more particularly to a reagent fingerprint development temperature control method applied to paper. BACKGROUND

[0002] In criminal scene investigation, in order to fix and extract evidence, technicians usually extract various involved items. Paper items are common involved items in various case scenes and are the main test materials for laboratory trace inspection.

[0003] The methods for developing fingerprints on paper evidence in the laboratory mainly include spraying, soaking, and fumigation with reagents. The current traditional fingerprint development equipment for paper items has the problems of large size, difficulty in carrying, slow heating, uneven heating of the items, and difficulty in use in field investigation. In general, paper evidence soaked with reagents needs to be dried and assisted by other equipment to develop fingerprints. The baking time ranges from several minutes to several hours, and the baking temperature range is also large. By adjusting the baking temperature and time, fingerprints can be quickly developed, providing a scientific basis for rapid reagent fingerprint development.

[0004] Currently, there is almost no research on the matching degree of temperature range and baking time for rapid baking and fingerprint development in domestic laboratories. Most of them are based on the reagent instruction manual, which greatly limits the efficiency of trace inspection. This is because the speed and effect of fingerprint development are not only related to the type and concentration of the developing reagent, but also directly related to the temperature, humidity, and equipment of the developing environment, which is difficult to verify experimentally. SUMMARY

[0005] The present application aims to at least partially solve the above technical problems, and provides a reagent fingerprint development temperature control method applied to paper. By exploring the process of developing latent fingerprints on paper using reagents in the laboratory, the correlation between the matching degree of baking temperature and time and the fingerprint development effect is studied by using equipment to bake and dry the soaked and sprayed paper. The purpose is to obtain the best effect of developing fingerprints in such laboratory applications, and then to summarize the corresponding rapid baking temperature and baking time.

[0006] The technical solution of the present application is a reagent fingerprint development temperature control method applied to paper, characterized by the following steps:

[0007] S1: In the same experimental environment, use the same reagent to soak the paper, and perform experiments under the same humidity and other small environmental conditions.

[0008] S2: Group A uses indanone as a fingerprint developing reagent; Group B uses indanone as a fingerprint developing reagent;

[0009] S3: The above-mentioned A group and B group experiments are respectively carried out, the appearance of the fingerprint is carried out in a short time under the condition that the temperature gradually increases until the fingerprint appears, and the fingerprint appearance effect is judged, and the optimal baking temperature range and the corresponding time are recorded;

[0010] S4: According to the experimental results, when the fingerprint appearance effect photo is obtained, the fingerprint is photographed according to the laboratory photography specification, so that the naked eye cannot distinguish the pixel points under the normal observation distance, and the potential fingerprint can be completely displayed, which is considered to be clear and complete.

[0011] Further, in step S3, the baking temperature is 135℃-145℃-155℃, 155℃-165℃, 165℃-175℃, 175℃-185℃, 185℃-195℃.

[0012] Further, in step S3, the baking time is 30S-60S.

[0013] Further, in step S2, A group is specifically that indanone is respectively experimented with object paper A4 paper, photo paper, kraft paper, packaging box paper and newspaper, and is recorded as AA4 paper, A photo paper, A kraft paper, A packaging box paper and A newspaper.

[0014] Further, in step S2, B group is specifically that indanone is respectively experimented with object paper A4 paper, photo paper, kraft paper, packaging box paper and newspaper, and is recorded as BA4 paper, B photo paper, B kraft paper, B packaging box paper and B newspaper.

[0015] Compared with the prior art, the beneficial effects are that the standardized experimental content is combined with different reagents and different paper evidence under the premise that the concentration of the specific reagent, the humidity of the paper, the same experimental environment and other factors remain stable, the baking temperature range and the time range data of each group are collected, the baking temperature and the matching time are recorded, and the optimal rapid baking temperature and time are explored by analyzing the variable factors.

[0016] The present application improves the test efficiency. In the original laboratory test mode, the evidence is sent back to the laboratory for fumigation and fingerprint appearance after extraction, and the fingerprint appearance usually takes 1 to 3 hours on average for each case. By using the method, each case can be detected in tens of seconds to 1 minute, which not only improves the test time, but also improves the work efficiency, saves manpower resources and time cost for laboratory test work. The original 100% laboratory test equipment is changed to on-site rapid detection and rapid comparison, and the test can be performed anytime and anywhere.

[0017] In order to better understand and implement, the present application is described in detail below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the AA4 paper of the present invention showing the fingerprint effect.

[0019] Figure 2 is the picture of the present invention for standard photographing of the fingerprint.

[0020] Figure 3 is the comparison picture of the fingerprint effect of the present invention.

[0021] Figure 4a is the AA4 paper of the present invention showing the baking effect at 135℃, 145℃, 155℃.

[0022] Figure 4b is the AA4 paper of the present invention showing the baking effect at 165℃, 175℃, 185℃, 195℃, 200℃.

[0023] Figure 5a is the A photo paper of the present invention showing the baking effect at 135℃, 145℃, 155℃, 165℃, 170℃.

[0024] Figure 5b is the A photo paper of the present invention showing the baking effect at 175℃, 185℃, 195℃, 200℃.

[0025] Figure 6a is the A kraft paper of the present invention showing the baking effect at 135℃, 145℃, 155℃, 165℃, 170℃.

[0026] Figure 6b is the A kraft paper of the present invention showing the baking effect at 175℃, 185℃, 195℃, 200℃.

[0027] Figure 7a is the A packaging box paper of the present invention showing the baking effect at 135℃, 145℃, 155℃, 165℃, 170℃.

[0028] Figure 7b is the A packaging box paper of the present invention showing the baking effect at 175℃, 185℃, 195℃, 200℃.

[0029] Figure 8a is the A newspaper of the present invention showing the baking effect at 135℃, 145℃, 155℃, 165℃, 170℃.

[0030] Figure 8b is the A newspaper of the present invention showing the baking effect at 175℃, 185℃, 195℃, 200℃.

[0031] Figure 9a is the BA4 paper of the present invention showing the baking effect at 135℃, 145℃, 155℃, 165℃, 170℃.

[0032] Figure 9b is the baking effect diagram of the BA4 paper of the present application at 135℃, 145℃, 155℃, 165℃, 170℃.

[0033] Figure 10a is the baking effect diagram of the B kraft paper of the present application at 135℃, 145℃, 155℃, 165℃, 170℃.

[0034] Figure 10b is the baking effect diagram of the B kraft paper of the present application at 175℃, 185℃, 195℃, 200℃.

[0035] Figure 11a is the baking effect diagram of the B packaging box paper of the present application at 135℃, 145℃, 155℃, 165℃, 170℃.

[0036] Figure 11b is the baking effect diagram of the B packaging box paper of the present application at 175℃, 185℃, 195℃, 200℃.

[0037] Figure 12a is the baking effect diagram of the B newspaper of the present application at 135℃, 145℃, 155℃, 165℃, 170℃. Figure 12b is the baking effect diagram of the B newspaper of the present application at 175℃, 185℃, 195℃, 200℃. DETAILED DESCRIPTION

[0038] The drawings are only used for illustrative description, and cannot be understood as a limitation to the patent; in order to better illustrate the embodiments, some components in the drawings are omitted, enlarged or reduced, and do not represent the actual product size; it can be understood by those skilled in the art that some well-known structures in the drawings and their descriptions can be omitted. The positional relationship described in the drawings is only used for illustrative description, and cannot be understood as a limitation to the patent.

[0039] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms “upper”, “lower”, “left”, “right” and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for illustrative description, and cannot be understood as a limitation to the patent, and for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0040] As Figure 1-12, the present application according to the reagent method for laboratory use to common paper is shown fingerprint, and the fingerprint effect is influenced by specific reagent, concentration, baking temperature, baking time and other factors, the method for controlling variable method is used, under the premise that specific reagent, concentration, humidity and other factors remain stable, the baking temperature, time control fingerprint effect method of showing.

[0041] First, set up experiments, experiments are carried out in the same experimental environment, using the same reagent to soak paper, the humidity is consistent (complete immersion, spraying), other environmental conditions with less influence factors are grouped and combined, indanone is used as fingerprint developing reagent and divided into group A, respectively with object paper A4 paper, photo paper, parchment paper, corrugated paper (express packaging box paper), newspaper, record as AA4 paper, A photo paper, A parchment paper, A packaging box paper, A newspaper, indanone is used as fingerprint developing reagent and divided into group B, respectively with object paper A4 paper, photo paper, parchment paper, corrugated paper (express packaging box paper), newspaper, record as BA4 paper, B photo paper, B parchment paper, B packaging box paper, B newspaper, two groups of experiments are carried out respectively, in accordance with the requirements of setting up experiments, that is, gradually increasing temperature from 135℃ 145℃ ~ 155℃, 155℃ ~ 165℃, 165℃ ~ 175℃, 175℃ ~ 185℃, 185℃ ~ 195℃ in a short time (30 seconds to a few minutes, seconds are represented by S, the same below) to show fingerprint experiment until the fingerprint is shown, and the fingerprint developing effect (clarity, integrity) is evaluated, the optimal baking temperature range and corresponding time are recorded, such as Figure 1 and table 1. Fingerprint clear and complete: under normal observation distance, the naked eye cannot distinguish pixel points as standard, fingerprint line reflection is clear, and line is obviously visible.

[0042] Table 1:

[0043]

[0044]

[0045]

[0046] For the effective factors of the control model, the study focuses on the analysis of five paper objects A4 paper, photo paper, kraft paper, corrugated paper (express packaging box paper), and newspaper with specific reagents (indanone, indanone) under laboratory procedures. The different baking temperature intervals and times are quantified, and the fingerprint effect (clarity and completeness) is evaluated. The experimental scene is recorded for further analysis, and the data from each group of experiments are collated and analyzed. Through grouping, group A uses indanone reagent, and group B uses indanone reagent for soaking and spraying on five objects A4 paper, photo paper, kraft paper, corrugated paper (packaging box), and newspaper until completely wet. They are placed in a rapid oven, and the baking temperature is 135℃-145℃-155℃, 155℃-165℃, 165℃-175℃, 175℃-185℃, 185℃-195℃, and above. Group A and group B have 180 groups of fingerprint effects and corresponding baking temperatures and times.

[0047] For the experimental results, when taking photos of fingerprint appearance effects, refer to laboratory photography standards to standardize fingerprint photography. At normal observation distance, the naked eye cannot distinguish pixels, and potential fingerprints can completely appear, which is considered clear and complete, as shown in Figure 2 、 Figure 3 , Figure 3 , where the top fingerprint effect photo shows clear and complete fingerprint lines, and the bottom fingerprint effect photo shows unclear and incomplete fingerprint lines.

[0048] Furthermore, under the premise that the fingerprint effect meets the requirements, record the optimal matching degree of the baking temperature interval and time in the experimental process, as shown in Table 2.

[0049] Table 2:

[0050]

[0051]

[0052] A4 paper under indanone reagent appears when the baking temperature is 175℃ and the baking time is 40 seconds, the fingerprint is clear and complete.

[0053] By dividing the samples into groups, Group A used ninhydrin reagent, and Group B used ninhydrin reagent. The samples were then soaked and sprayed onto five different substrates—A4 paper, photographic paper, kraft paper, corrugated cardboard (packaging boxes), and newspaper—until completely wet. These were placed in a rapid baking oven and baked at temperatures ranging from 135℃ to 145℃ to 155℃, 155℃ to 165℃, 165℃ to 175℃, 175℃ to 185℃, and 185℃ to 195℃ and above, over a period of 30 seconds to several minutes (each baking time being 10 seconds). A total of 180 fingerprint samples were obtained from both groups, along with their corresponding baking temperatures and times. Under consistent experimental conditions regarding temperature, drying, light intensity, and reagent brand and concentration, baking temperature and time were identified as the primary factors influencing fingerprint development.

[0054] The experimental results for groups A and B are shown in Figure 4-12:

[0055] like Figure 4a and Figure 4b In the analysis of AA4, the optimal baking temperature range and corresponding time under the condition of clear fingerprint effect are: 175℃ for 40S~50S; 155℃ for 40S~50S; 185℃ for 30S~40S. The fingerprint effect is poor in the two boundary ranges of slightly lower temperature and slightly higher temperature. As the temperature is increased, the fingerprint tends to be stable in the range of 155℃ to 185℃.

[0056] like Figure 5a and Figure 5b In the analysis of photo A, the optimal baking temperature range and corresponding time for photo A under the condition of clear fingerprint effect are: 165℃ for 40 seconds. The fingerprint effect is poor in the two boundary ranges of slightly lower temperature and slightly higher temperature. As the temperature is increased, the fingerprint tends to stabilize at around 165℃ with a baking time of 30 seconds to 50 seconds.

[0057] like Figure 6a and Figure 6b In the analysis of cowhide A, the optimal baking temperature range and corresponding time for cowhide A under the condition of clear fingerprint effect are: 165℃ for 40 seconds. The fingerprint effect is poor in the two boundary ranges of slightly lower temperature and slightly higher temperature. As the temperature is increased, the fingerprint tends to stabilize at around 165℃ with a baking time of 30 to 50 seconds.

[0058] like Figure 7a and Figure 7b In the analysis of packaging box A, the optimal baking temperature range and corresponding time for packaging box A under the condition of clear fingerprint effect are as follows: no clear fingerprint appears under various baking temperatures and times.

[0059] like Figure 8a and Figure 8bIn the A newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 165°C matching 40S; the fingerprint effect is poor in the slightly low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 165°C with a roasting time of about 40S.

[0060] In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S. Figure 9a Figure 9b In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S.

[0061] In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S. Figure 10a Figure 10b In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S.

[0062] In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S. Figure 11a Figure 11b In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S.

[0063] In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S. Figure 12a Figure 12b In the B newspaper, the optimal roasting temperature interval and corresponding time for clear fingerprint effect are: 175°C matching 20S-30S; the fingerprint effect is poor in the low temperature and slightly high temperature boundary interval in the whole interval, and the fingerprint tends to be stable around 175°C with a roasting time of about 20S-30S.

[0064] The fingerprint processing effect is equivalent to the original laboratory processing, and the naked eye cannot distinguish the pixels at a normal observation distance. The fingerprint is clear and visible, and the appearance effect reaches the identification level.

[0065] ​​​​The detection rate of fingerprints on paper in the cases handled by the laboratory in Y district of G city in 2023-2024 reached 72%. The baking temperature and time were analyzed. The extraction of paper evidence at the scene greatly shortened the detection time and improved the detection rate compared with the previous evidence sent to the laboratory for processing. This method has practical application value in the on-site processing of paper evidence.

[0066] The analysis of the experimental results (only the set temperature range was analyzed) showed that the low temperature range specified in the original reagent instruction included 100℃ or less, room temperature, and constant temperature. According to the instruction, the actual laboratory work has verified that the baking time is slightly longer or longer (several tens of minutes to several hours), and the fingerprints can be clearly visible, meeting the conditions specified in the reagent instruction.

[0067] As the experimental temperature continued to rise, 135℃-145℃-155℃, 155℃-165℃, 165℃-175℃, 175℃-185℃, 185℃-195℃... Group A: Tables 3 and 4

[0068] Table 3

[0069]

[0070]

[0071]

[0072] ① AA4 in the 155℃-185℃ temperature range, the baking time in the 30S-50S range, the fingerprint effect is clear and complete, among which when the baking temperature is adjusted to 185℃, 175℃, 155℃, the baking time is 30S-40S, 40S-50S, 40S-50S respectively, the fingerprint effect reaches the best. In other temperature ranges, the high temperature range 185℃ to 195℃, baking for 40S-50S or more, the paper appears to be curled, wrinkled, and slightly smoky, the fingerprint effect is dark and blurred.

[0073] ② A photo in the 155℃-185℃ temperature range, the baking time in the 30S-50S range, the fingerprint effect is clear and complete, among which when the baking temperature is adjusted to 185℃, 165℃, 155℃, the baking time is 30S-40S, 40S, 40S respectively, the fingerprint effect reaches the best. In the 170℃-175℃ range, the baking time is 30S-50S or more, the fingerprint effect is poor and cannot clearly show the fingerprint.

[0074] ③ The optimal baking temperature range and corresponding time for clear A cowhide fingerprint effect are:

[0075] 165℃ match 40S; while in other temperature intervals and 30S-50S baking time, the fingerprint effect is poor, can not distinguish the lines.

[0076] (4) A packaging box in each experimental baking temperature and time baking, no clear fingerprint appears;

[0077] (5) A newspaper fingerprint effect clear conditions its optimal baking temperature interval and corresponding time is:

[0078] 165℃ match 40S; while in other temperature intervals and 30S-50S baking time, the fingerprint effect is poor, can not distinguish the lines.

[0079] Table 4

[0080]

[0081]

[0082]

[0083] ① BA4 at 155℃, 175℃, 185℃, baking time is 40S, 40S-50S, 40S, the fingerprint effect is clear, complete, other temperature intervals 165℃, 170℃, baking time 30S-50S, the fingerprint is relatively clear, when the temperature to 195℃, baking 30S-50S or more, the paper appears curl, wrinkle, smoke, fingerprint effect is black, blurred.

[0084] ② B leather fingerprint effect clear conditions its optimal baking temperature interval and corresponding time is: 175℃ match 30S-40S; 165℃-170℃ match 40S; other temperatures 175℃, 50S, 155℃, 40S-50S and 185℃, 30S-40S, the fingerprint lines are not clear, the fingerprint effect is poor;

[0085] ③ B packaging box at 175℃ match 80S-100S, the fingerprint effect is clear and complete; in other baking temperature and time baking, no clear fingerprint appears;

[0086] (4) B newspaper at 175℃ match 20S-30S, the fingerprint effect is clear and complete; in other baking temperature and time baking, no clear fingerprint appears;

[0087] The experimental results are as follows:

[0088] Group A:

[0089] A4 paper in the range of 175℃-185℃ near the baking time of 40S, the fingerprint effect is best;

[0090] A leather in the range of 155℃ ~ 185℃, 40S, fingerprint effect is best; while in other temperature intervals, time, fingerprint effect is poor, can not distinguish the lines;

[0091] A leather in the range of 155℃ ~ 185℃, 40S, fingerprint effect is best; while in other temperature intervals, time, fingerprint effect is poor, can not distinguish the lines;

[0092] A package in the set temperature range, short time, no fingerprint;

[0093] A newspaper in the range of 155℃ ~ 185℃, 40S, fingerprint effect is best; while in other temperature intervals, time, fingerprint effect is poor, can not distinguish the lines;

[0094] B group:

[0095] A4 paper in the range of 155℃, 175℃, 185℃, 40S, fingerprint effect is best;

[0096] B leather in the range of 155℃ ~ 185℃, 40S, fingerprint effect is best; while in other temperature intervals, time, fingerprint effect is poor, can not distinguish the lines;

[0097] B package in the range of 155℃ ~ 185℃, 40S, fingerprint effect is best; while in other temperature intervals, time, fingerprint effect is poor, can not distinguish the lines;

[0098] B newspaper in the range of 155℃ ~ 185℃, 40S, fingerprint effect is best; while in other temperature intervals, time, fingerprint effect is poor, can not distinguish the lines.

[0099] Fingerprint effect changes with temperature and baking time, in the high temperature area, the penetration of the paper with thick thickness is stronger, and the process of fingerprinting requires higher temperature and time (or low temperature, long time baking), while the paper with thin thickness is easy to curl and even smoke in high temperature area.

[0100] In the original laboratory test mode, the extract evidence is sent back to the laboratory for fumigation and fingerprinting, which usually takes 1 to 3 hours per case. Using this method, each case can be detected in tens of seconds to 1 minute, which not only improves the test time, but also improves the work efficiency, saves manpower resources and time cost for laboratory test work. In the original 100% use of laboratory test equipment, it is changed to on-site fast detection, fast comparison, and can be tested anytime, anywhere.

[0101] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Based on the above description, any other variations or changes can be made by those skilled in the art without departing from the spirit and principles of the present application. It is not necessary to list all the embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall fall within the scope of the claims of the present application.

Claims

1. A temperature control method for reagent-developed fingerprints applied to paper, characterized in that, Includes the following steps: S1: Conduct experiments in the same experimental environment, using the same reagent to soak the paper, and combine groups of experiments under environmental conditions where humidity is consistent and other influencing factors are minimal. S2: Those using ninhydrin as the fingerprint developing reagent are divided into group A; those using ninhydrin as the fingerprint developing reagent are divided into group B. S3: The above experiments A and B were conducted separately. The fingerprint development experiment was carried out by gradually increasing the temperature in a short period of time, in accordance with the requirements of the experiment, until the fingerprint appeared. The fingerprint development effect was evaluated, and the optimal baking temperature range and corresponding time were recorded. S4: Based on the experimental results, when obtaining photos of the fingerprint display effect, refer to the laboratory photography specifications and take photos of the fingerprint in a standardized manner so that the pixels cannot be distinguished by the naked eye at normal observation distance and the potential fingerprint can be fully displayed, which is considered clear and complete.

2. The method for temperature control of reagent-developed fingerprints applied to paper according to claim 1, characterized in that: In step S3, the baking temperature is 135℃~145℃~155℃, 155℃~165℃, 165℃~175℃, 175℃~185℃, or 185℃~195℃.

3. The method for temperature control of reagent-developed fingerprints applied to paper according to claim 2, characterized in that: In step S3, the baking time is 30 to 60 seconds.

4. The method for temperature control of reagent-developed fingerprints applied to paper according to claim 3, characterized in that: In step S2, group A specifically involves indanedione being tested with A4 paper, photographic paper, kraft paper, packaging box paper, and newspaper, and the results are recorded as AA4 paper, A photographic paper, A kraft paper, A packaging box paper, and A newspaper.

5. The temperature control method for reagent-developed fingerprints applied to paper according to claim 4, characterized in that: In step S2, group B specifically involves ninhydrin being tested with A4 paper, photographic paper, kraft paper, packaging box paper, and newspaper, and the results are recorded as BA4 paper, B photographic paper, B kraft paper, B packaging box paper, and B newspaper.

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