Arthur Gwynn Geiger
Arthur Geiger is the man involved in the blackmail scheme to obtain a grand from General Sternwood for supposed gambling debts accrued by Carmen. He's middle-aged, overweight, and runs a rare bookstore on Hollywood Boulevard that's a front for his illegal pornography racket. Geiger loans out pornographic material from the back room of the bookstore. He lives in a lavishly decorated house with his lover Carol Lundgren. There are also hints that Geiger may be bisexual.
When Marlowe stakes out Geiger's home, he sees a bright flash of light and then hears three gunshots. Marlowe breaks into the house to find Geiger dead and Carmen alive but naked. After Marlowe brings Carmen home, he returns to Geiger's home to find that his body has been removed. It turns out that Lundgren had hidden his body to prevent the police from finding out so that he could avenge Geiger's death.