Mr. O'Brien's research interests involve the examination of trace evidence by analytical instrumentation. His research has included the analysis of gunshot residue with atomic absorption spectroscopy and scanning electron microscopy. In addition, his research has included the variables associated with the determination of muzzle to target distance in shooting cases. He utilizes his research to evaluate gunshot residue, distance determination and bloodstain pattern evidence at crime scenes in order to reconstruct a shooting incident.
Mr. O'Brien graduated with a B.S. in chemistry from the University of Connecticut and an M.S. in chemistry from Saint Joseph's College in Connecticut.
He worked at the Connecticut Forensic Science Laboratory for over 28 years. He has gone to numerous crime scenes and examined and analyzed physical evidence in hundreds of cases at the laboratory. As the Deputy Director of Identification in the laboratory, he directed staff and operations for the firearm/tool mark, fingerprint, document/imprint, electronic and digital imaging and computer crime sections of the laboratory. He coordinated the laboratory internship program for over 20 years. He worked extensively on crime scene reconstructions involving shootings and blood stain pattern interpretation and testified as an expert witness for the prosecution and defense over two hundred twenty times in numerous states. He attended numerous specialized forensic sciences courses at the FBI Academy and is trained as an inspector by ASCLD/LAB.