Jeff Regan, Investigator, was one of countless private detective series that proliferated in the years following WWII. The series initially featured Jack Webb in the title role, who was coming off his work in Pat Novak for Hire, followed by Johnny Madero, Pier 23. The series premiered July 10, 1948, over the CBS network. Originally promoted as Joe Canto, Private Eye, the series was never actually broadcast under that name. However, Barton Yarborough, Jack Webb's first partner in Dragnet, would make a guest appearance in the show playing a bit part named Joe Canto. The series was sometimes incorrectly called The Lyon's Eye by collectors because Regan frequently opened each show stating "I'm Jeff Regan, they call me The Lyon's Eye" or something similar.

The first run of Jeff Regan ran from July 10 to December 18, 1948. Webb continued to play a hard-boiled character as in previous roles, but this time with a better relationship with the police. Webb left the show after 24 episodes when CBS declined his request for a $15 per episode raise. He returned for a brief run on a revived Pat Novak for Hire before premiering on his signature program, Dragnet, in June 1949.