Frank Briggs (played by Henry Beckman) was a retired Baltimore Police Detective who worked on the five murder cases generated by Eugene Victor Tooms in 1933. When the killer returned in 1963, Briggs registered his interest in working the case but was refused as, by this time, he had been relegated to a desk job. However, he conducted his own personal investigation which included surveillance of Tooms. He retired in 1968 after 45 years as a cop.
Briggs assisted FBI Special Agents Mulder and Scully when Tooms came out of hibernation and began to kill again in 1993. Briggs noted that Tooms would collect small personal items from his victims, a pattern later noticed by Mulder. By this time, Briggs was living at the Lynne Acres Retirement Home in Baltimore, Maryland.
When Tooms was released from custody and continued to kill, Briggs assisted Scully in finding a 1963 victim buried in concrete using his "gut-feeling".