several years ago I worked in a library and remember seeing a mystery novel in which Harpo Marx was the main suspect. Or something to that effect. It was fiction of course.
does anyone have any idea what book I’m talking about? I’d really like to read it. It sounded interesting 
Well, Ukulele Ike probably knows for certain, but I think you’re looking for You Bet Your Life by Stuart Kaminsky. Kaminsky’s detective, Toby Peters, lives in 1940’s Hollywood and has adventures with a variety of now-dead stars.
In the meantime, I could lend you my copy of The Gracie Allen Murder Case by S.S. Van Dine.