Dressed to Kill(1980)

Down on his luck private investigator Michael Shayne (Lloyd Nolan) is headed to the courthouse to marry showgirl Joanne (Mary Beth Hughes) when they hear screams from an adjacent apartment.  Rushing in, they find two dead bodies seated at a dining table.  Theater director Lou Lathrop and his mistress Desiree have been shot.  Shayne calls the newspaper, and negotiates a big payoff for notifying them before the police.

The main suspect is Julian Davis, as he owed Lou a lot of money.  Shayne also negotiates a big payoff for hiding evidence that implicates Julian, with a promise of a windfall if he finds the killer.  Shayne is frequently interrupted by Joanne, demanding to know when they will finally get married.

Lathrop’s one great theater hit was 20 years ago.  The night he died, he had hosted a reunion for the cast of that show.  They suspect the killer was a member of the cast.  Clues point to Carlo Ralph.  Lou ruined Carlo’s career and stole away his wife, Desiree.  However, Carlo supposedly died in the war.

It turns out Otto, the doorman, is really Carlo. He served in the war and was in a German POW camp.  He changed so much from the war and being a POW that no one recognized him.  He wanted revenge on Lou for ruining his life.  Shayne solves the murder and gets Carlo arrested.  However, Joanne got tired of waiting for Shayne and married her old boyfriend Gus.