View the photographs released by the Los Angeles police.
Los Angeles (CNN) -- Los Angeles authorities expanded their investigation into the Grim Sleeper serial killer case Thursday by asking for the public's help in identifying women in 180 photographs whose images were found in the suspect's home this summer.
Police are trying to determine if there are additional killings among the more than 100 women depicted in the photos.
Last July, 57-year-old Lonnie David Franklin Jr. was arrested and charged with 10 murders and one attempted murder dating back to 1985, and Los Angeles police spent hundreds of hours sifting through thousands of photographs, Polaroids and videotape found in Franklin's house.
The bodies of victims, many working as prostitutes, were all found in close proximity to each other in a neighborhood formerly known as South Central Los Angeles.
Franklin, a mechanic who once worked for the LAPD, was arrested in July after police say they matched his DNA with DNA left on some of the victims. Police were led to Franklin after his 28-year-old son got arrested and gave a DNA swab, authorities said.
Authorities said they narrowed down the confiscated images down to 180 photographs, some of them duplicates of the same women.
At a media conference attended by Mayor Antonio Villaraigosa and Police Chief Charlie Beck, authorities said they had difficulty determining whether some of the women were alive or dead in the photos.
"We cannot tell," Beck said. "Obviously, as all of you can see, some of them are animated and some are not. It's impossible to tell by the photographs.
Robbery Homicide Detective Dennis Kilcoyne said police have a responsibility to try to determine the whereabouts of the women.
"These are clearly photos of women that Mr. Franklin had contact with," said Kilcoyne. "We have a responsibility to identify these women. They may be alive and well, but we need to be certain."
"If there's nothing we glean from this, we are able to fill in the timeline of Mr. Franklin's life, and that's one of our goals as well," Kilcoyne said.
He declined to talk about the context in which the women's images appeared.
"The lifestyle or the situation that these women are in would defeat our plea with the public," Kilcoyne said.
Police are not sure where the women in the images resided, because Franklin's movements throughout his life are not yet ascertained, authorities said.
"His travel habits are unknown to us," Kilcoyne said. "We believe he spent the majority of his life right here in the city of Los Angeles."