Mr. Gahn holds a B.S. in Psychology from Saint Louis University. He graduated from Marquette University Law School in 1984. Prior to entering law school, he served 10 years in the United States Army as a Military Police Officer and Criminal Investigation Division (CID) Field Office Commander. While in the service and stationed at Fort Belvoir, Virginia, he attended George Washington University and received a Master of Forensic Sciences Degree in 1980.
Upon graduation from Marquette Law School, Mr. Gahn spent 31 years with the Milwaukee County District Attorney’s Office. His primary duty as an Assistant District Attorney (ADA) for Milwaukee County was the prosecution of homicide and sexual assault cases that involved the use of DNA evidence or other forensic science disciplines. From 2001 to his retirement in 2015, Mr. Gahn filled a DOJ funded position as the statewide DNA prosecutor with duties and responsibilities to assist prosecutors and law enforcement throughout Wisconsin with DNA related matters, as well general forensic science issues.
In 1998 Mr. Gahn was appointed by the U.S. Department of Justice to the National Commission on the Future of DNA evidence. In 1999 the Federal Bureau of Investigation formally recognized him as a pioneer in DNA technology in the courtroom. The National Institute of Justice formally recognized him in 2000 as an innovator in the field of DNA evidence. In 2010 he was selected to serve as an advisory member under the National Science and Technology Council Subcommittee on Forensic Science. On April 21, 2015, at a ceremony in Washington D.C., Mr. Gahn received the Allied Professional Award from Attorney General Eric Holder for his work with DNA evidence on behalf of victims of crime. In 2015 the State Bar of Wisconsin selected him to receive the Lifetime Legal Innovator Award for his work as an Assistant District Attorney in Milwaukee County. He has received numerous other awards and recognitions during his career as a prosecutor for Milwaukee County.
Mr. Gahn has lectured extensively around the country on the use of DNA evidence and the forensic sciences during his years as an ADA. He has taught prosecutors, law enforcement officers, and sexual assault nurse examiners about DNA evidence and DNA technology and forensic science. He has taught DNA evidence for Wisconsin trial court and appellate judges.
Mr. Gahn is currently an Adjunct Professor of Law at Marquette University Law School teaching Forensic Science and the Law.