Police in Los Angeles, California, are searching for information on a suspected serial killer who has murdered at least 11 people in a two-part spree of violence that has plagued the city since 1985.CNN: Reward Offered for "Grim Sleeper Serial Killer Authorities say the killer was dubbed the "Grim Sleeper" because of the long stretches of time between each of the murders.CNN: Police hunt 'Grim Sleeper' serial killer

Despite years of detective work, authorities have not made any arrests in connection with the series of murders allegedly committed by the suspect known as the "Grim Sleeper." In February 2009, police released a 911 call made shortly after a 1987 murder, in hopes of cracking the case. The anonymous caller can be heard telling authorities that "The guy that dropped her off was driving a white and blue Dodge van. He threw her out. ... He threw a gas tank on top of her. All that you can see sticking out is her feet."CNN: Police hunt 'Grim Sleeper' serial killer The caller also gave police the van's license plate number. In addition to the 911 tape, authorities also released a photo of a church van possibly used to dump one of the murder victims.Los Angeles Times: 1987 tape may hold clue to serial killer (February 25, 2009) NBC Los Angeles: Police Release Serial Killer 911 Recording (February 25, 2009)