In 1929 Kirk became professor of biochemistry at UC Berkeley. According to Kirk, he first became interested in forensic science in his early days as a teacher after a student asked if it could be determined if a dog had died of poisoning. Forensic science permanently piqued his interest when authorities asked him to do a microscopic examination of a rape victim's clothing. He found fibers from the attacker's shirt and this evidence resulted in a conviction. In 1937, Kirk became leader of UC Berkeley's criminology program. Due to his extensive experience in microscopy, Kirk was asked to join the Manhattan Project where he worked on the process to isolate fissionableplutonium from 1942 to 1945. When he returned to Berkeley, he created a major in technical criminology and when August Vollmer established the UC School of Criminology, Kirk was appointed to chair the criminalistics department. Kirk was also an avid supporter of Locard's exchange principle. As a result of his detailed descriptions of the principle, Kirk's words have repeatedly been mistaken for those of Edmond Locard himself. Unlike others before him, Kirk understood the limits of the principle and argued for caution in the interpretation of exchange evidence. Kirk is best known for his work in the Sam Sheppard case. On January 22, 1955 - one month after Sheppard's conviction - Kirk visited the scene of the crime after which he wrote an extensive report primarily based on bloodstain pattern analysis. A motion for a retrial had been denied in 1955, but this decision was overturned in 1964 and in 1966, the Supreme Court upheld the decision for a retrial. Later that same year, Kirk testified at the retrial, which led to Sheppard's acquittal. Kirk's testimony embarrassedSamuel Gerber, a senior member of the American Academy of Forensic Sciences who was working for the prosecution and believed in Sheppard's guilt. Kirk was denied AAFS membership, but he still left his mark on the organization. The highest honor awarded in the criminalistics section of the AAFS is the Paul L. Kirk Award. Dr. Kirk's photographs, analysis, and testimony from the Sam Sheppard case can be seen at http://engagedscholarship.csuohio.edu/kirk_photos/index.2.html.
