Now that police have his DNA in a database, they're looking into whether he is connected to at least 30 unsolved murders over the years.
Franklin was arrested Wednesday morning at his South L.A. home and is being held without bail.
Many of the women he's accused of killing were sexually assaulted and shot. Detectives reportedly seized guns from Franklin's home, but LAPD Chief Charlie Beck would not discuss what they found during their search.
"I'd be way ahead of the detectives if I was to give details of what was found in the house. I will say that we have some very promising evidence that has been recovered from his residence that I believe will connect him to these crimes and maybe some others," Beck said.
Meanwhile, police said crime is down in L.A. for the eighth year in a row.
"Despite the biggest economic crisis since the Great Depression, our unwavering commitment to public safety has yielded tangible, positive results," Mayor Antonio Villaraigosa said.
Violent crimes are down 11 percent from last year, property crimes have dipped 5.3 percent and gang-related crimes are down 9.4 percent.
Beck said the city is safer because police are working closely with the communities they protect. He also praised innovative anti-gang initiatives such as Summer Night Lights, which keeps kids in troubled neighborhoods busy with sports and recreational activities at public parks.
"Cops are the most important thing (in public safety) ... but we leverage our effectiveness through community," Beck said. "The standards that a community sets for itself are much longer lasting than the standards that a police department sets for its community."
While the overall crime rate was down, homicides increased slightly in the city during the first half of the year compared to the same period last year.
From January through June, 150 homicides were reported to the Los Angeles Police Department, which is six more than last year, up 4.2 percent.
Gangs are blamed for more than half the homicides -- 82. That total is unchanged from last year, but the number of shooting victims attributed to gangs rose 6.6 percent, from 485 in the first half of 2009, to 517 in 2010.
Mayor Antonio Villaraigosa said L.A. is one of the most under policed big cities in the United States, and due to budget cuts, police have had their overtime funding cut. Beck said as soon as the city is able to do so, it will restore that funding for officers.
According to Villaraigosa and Beck, the statistics indicate the Los Angeles is the second-safest big city in the country, next to New York. However, they point out New York uses a different system for measuring crime rates, which does not match with federal government standards.
City News Service contributed to this story.