Analyzing the protein residues sticking to bullets can reveal what organs were crossed by a projectile - a case for forensic proteomics.
Standard forensic procedures to examine bullets after an exchange of fire include a mechanical or ballistic reconstruction of the event. While this is routine to identify which projectile hit a subject by DNA analysis of biological material on the surface of the projectile, it is rather difficult to determine which projectile caused the lethal injury - often the crucial point with regard to legal proceedings. With respect to fundamental law it is the duty of the public authority to make every endeavor in order to solve every homicide case. To improve forensic examinations we present a forensic proteomic method to investigate biological material from a projectile's surface and determine the tissues traversed by it. To obtain a range of relevant samples, different major bovine organs were penetrated with projectiles experimentally. After tryptic "on-surface" digestion, mass spectrometry-based proteome analysis and statistical data analysis, we were able to achieve a cross-validated organ classification accuracy of over 99%. Different types of anticipated external variables exhibited no prominent influence on the findings. In addition, shooting experiments were performed to validate the results. Finally, we show that these concepts could be applied to a real case of murder in order to substantially improve the forensic reconstruction.
Find the original paper here.
A press release (in German) on the paper can be found here