Police investigating the man accused of the "Grim Sleeper" serial killings of prostitutes and other women in Los Angeles are expanding their review of cold cases to see if he is connected to them, a police official said Tuesday.

Cmdr. Andrew Smith told The Associated Press that detectives are looking at as many as 250 unresolved files dating back to the late 1970s and early 1980s to see whether there are any links to Lonnie Franklin Jr.

"We just want to make sure nothing fell through the cracks," Smith said.

Franklin has pleaded not guilty to 10 murders and one count of attempted murder. Most of the victims linked to the "Grim Sleeper" were found in alleyways within a few miles of Franklin's home. They were killed after some kind of sexual contact.

Prosecutors are seeking the death penalty against Franklin.

The killings got their name because of an apparent long gap between some of the deaths, which began in the 1980s and extended into the 2000s.

Franklin, a mechanic, was arrested in July 2010. Police now theorize there never was a break in the killings.

Detectives are also looking to establish the identities of women in as many as 51 photos found stashed in a fridge in Franklin's South Los Angeles house.

One of the women in the stash, Janecia Peters, was allegedly killed by Franklin.