When detectives searched Franklin's home and surrounding property, they found more than 1,000 photos and hundreds of hours of home video footage in his possession.
"It's a long period of time that he's been taking pictures," Kilcoyne said.
Authorities working on the case said they had been trying to identify the women in the images for months.
Franklin pleaded not guilty to the charges on Aug. 23, 2010, during a court appearance. He remains in custody.
Pensanti also criticized investigators for comments made at a press conference, which she said were "a deliberate tainting of public opinion and the jury pool."
"Sadly, the public officials who have the duty to uphold the Constitution have forgotten the basics in their desire for sensationalism and are jeopardizing Lonnie Franklin's chance for a fair trial," she said.
According to the attorney general's office, the suspect's son was arrested and convicted on a felony weapons charge and swabbed for DNA last year. When his DNA was entered into the database of convicted felons, detectives were alerted to a partial match to evidence found at the "Grim Sleeper" crime scenes.