A method is disclosed for analyzing a biological sample by 
antibody profiling for identifying forensic samples or for detecting the presence of an 
analyte. In an illustrative embodiment of the invention, the 
analyte is a 
drug, such as marijuana, cocaine, 
methamphetamine, 
methyltestosterone, or mesterolone. The method involves attaching antigens to the surface of a 
solid support in a preselected pattern to form an array wherein the locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to antigens in the array, thereby forming immune complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, thereby forming an 
antibody profile. Forensic samples are identified by comparing a sample from an 
unknown source with a sample from a known source. Further, an 
assay, such as a test for illegal 
drug use, can be coupled to a test for identity such that the results of the 
assay can be positively correlated to the subject's identity.