(CNN) -- Los Angeles police are searching for a serial killer dubbed the "Grim Sleeper," who is thought to have killed 11 people.



Alicia Alexander was one of the Grim Sleeper's victims in the 1980s.



The killer, who police say murdered from 1985 to 2007, was nicknamed the Grim Sleeper because he seemed to take a break between homicides, police said.



Authorities this week released a 9-1-1 tape recorded shortly after a killing in 1987, in the hope of producing clues.



"Yes ... I'd like to report a murder," an anonymous caller says on the tape. "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."  Watch the hunt for a serial killer »



Police found the scene just as the caller described and found the van. But they are still searching for the caller and members of the now-defunct church that owned the van.



The killer is wanted in 11 deaths and another homicide attempt, police say.



Detectives say they have the Grim Sleeper's DNA, and a $500,000 reward has been offered for information leading to an arrest and prosecution. The killer shot his victims, police said.



Porter Alexander has waited two decades for the Grim Sleeper's arrest. His daughter Alicia Alexander became the Grim Sleeper's eighth victim in 1988, police say.



"No one should have to face anything like this," he said. "To experience their daughters or sons taken away as early as she was."



CNN's Kara Finnstrom contributed to this report.
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