During his ten years as a police officer, he worked a variety of assignments, yet none stayed with him as much as his tour of duty in Vietnam.
He also penned three books in the Able Team series, which was a spin-off of the immensely popular Mack Bolan Exceutioner novels.
He wrote the final installment in the Vietnam Ground Zero series, (published as Zebra Cube in the Heroes trilogy), using the pseudonym Robert Baxter.
After writing over 30 books, Cain pulled the plug on his word processor in 1990 and became a private investigator in Los Angeles.
He began teaching the Learning Annex's Course #523: How To Get Anything on Anybody in the mid-1990s, and wrote two investigative manuals to go along with it: Trick Questions (And Other Trade Secrets of an L.A. County P.I.)