It Happened One Knife by Jeffrey Cohen

In ten words or less: Legendary comedy team involved in decades old suspicious death.

Review: Elliot Freed is reopening his all-comedy movie theatre, Comedy Tonight, and his life is looking rosy. His ex-wife Sharon is even hinting that a reconciliation might be possible.
Elliot feels so optimistic he agrees to screen his young projectionist's film that was made as a college project. The film, a violent and bloody Western, is not to his taste, but a film distributor in the audience thinks he can sell it to a studio. But after the screening, the film goes missing, and everyone blames Elliot.
Elliot is busy planning a showing of "Cracked Ice," a vintage comedy featuring the legendary team of Harry Lillis and Les Townes. It's his good fortune to get Harry Lillis to appear at the theatre for the screening, and Les Townes makes a surprise appearance. Lillis confides to Elliot that Townes killed his wife years ago, and Elliot decides to investigate the death, which was ruled an accident.

Why bother? A healthy dose of show biz history adds to this mystery. Readers of Stuart Kaminsky's Toby Peters series should check this out.