Death Paints the Picture — Lawrence Lariar

Frist in a series: A comic book artist is drawn into an elaborate game of murder when he visits an isolated country estate in Woodstock.
 
Lawrence Lariar was one the most popular cartoonists of the twentieth century. But from the 1940s through the 1960s, he also crafted a line of lean and mean detective and mystery novels under his own name as well as the pseudonyms Michael Stark, Adam Knight, Michael Lawrence, and Marston La France. Lariar now gets his due as a leading artist in hardboiled crime fiction.
 
A graphic artist and true crime buff, Homer Bull is always looking for a good murder for his syndicated comic strip. He just never expects to be invited to one -- courtesy of his old pal Hugo Shipley, a wealthy illustrator who's notorious for his practical jokes. But when Shipley himself drops dead from an apparent self-inflicted gunshot wound, it's no laughing matter.
 
Not that the other guests have a sense of humor. Among them, a dry tobacco magnate, a dull-witted gangster, a libelous newspaper reporter, and Homer's ex-wife, a shallow doll who dumped him for a career in modeling. All but Homer are quick to accept the suicide bunk. Maybe that's because all but Homer have their own sordid secrets and motives. And not one of them is leaving Shipley's isolated estate before Homer finds his friend's killer.
 
Death Paints the Picture is the 1st book in the Homer Bull & Hank MacAndrews Mysteries, but you may enjoy reading the series in any order.