I can’t find this anywhere in Wikipedia’s lists of TV series, but I remember in the late 70s there was a detective series called something like “The Eddie (something) Mysteries” or “The Eddie (something) Files.”* It sticks in my mind because it seemed to feature a relatively young, nondescript guy with no particular gimmick (not an ex-con, not a Catholic priest, not smarming around in a rumpled trench coat), and they really were mysteries, at least to my young self – the actual killer was never revealed until the end of the program.
I remember the opening sequence was a voiceover by the protagonist as it showed a hand laying out black and white photographs of that week’s principals on a desk.
*My mind keeps interjecting it was “The Eddie Haskell Mysteries” but I know that can’t be right.
When I google ‘70’s tv eddie mysteries’ this thread is the second hit. However, the first hit is a 70’s TV site, which mentions the ‘Eddie Capra’ Mysteries.
Wikipedia apparently also has pages for each season of American television - I spotted Eddie Capra on the 78-79 page, but since it’s old and only ran one 13 episode season, it is not noteworthy enough to have its OWN wiki page.