" According to John Douglas, fully 72 percent of serial killers are “preoccupied with fetishism during their formative years.” The fetishistic impulses of serial killers account for their tendency to take “trophies” from their murder victims—anything from wallets to underpants to body parts. These items—which the killers use to relive their crimes in fantasy, often while masturbating—are essentially fetish objects, providing them with intense, perverted pleasure. "

― Harold Schechter , The Serial Killer Files: The Who, What, Where, How, and Why of the World's Most Terrifying Murderers