The 30- or 40-something dark-haired male on the cover of these games appears to be the same character, but it's not clear to me which. Is it one of the in-game characters?
Honestly, I think it's just 'Generic 1920's stereotype'. While I agree that he's got a tommy gun in both pictures, his facial structure looks wrong for being Michael McGlen. He actually looks closer to Joe Diamond, if it wasn't for Joe Diamond having a blue suit. Michael McGlen would be closest, without going over, but I think the cover art characters are just generic characters and no actual investigator.
If I had to guess, it would be Michael McGlen due to the fact that he is rocking a tommygun.