(Reuters) - Amid ongoing efforts to address a backlog of unanalyzed rape kits that go untested throughout the country, California lawmakers passed a bill on Friday requiring law enforcement to process the evidence within a certain time frame.

The bill next goes for a procedural approval in the state Assembly next week before heading to Governor Jerry Brown's desk for his signature. Brown vetoed a pilot program in 2011 that would have required certain counties to process their backlogged rape kits.

But the latest measure, which takes a different approach by setting up a timeline for rape kit processing, received wide bipartisan support in Sacramento after several amendments extended the amount of time law enforcement would have to process the kits.

The bill, which passed through the state Senate unanimously, would require hospitals to submit rape kits to forensic labs within five days of collecting the DNA evidence from a sexual assault victim.

Law enforcement would have 20 days to do so. Once a forensic lab receives a rape kit, they would have 120 days to process it.   

"Testing this evidence gets the DNA from the crime into a national database, tells rape victims we care and helps ensure that rapists are caught and convicted," said state Assembly member Nancy Skinner, who authored the bill.

Skinner's bill comes after an audit by a district attorney and local law enforcement officials found more than 1,900 unprocessed rape kits within the Bay Area's Alameda County alone.

Rape kits holding DNA evidence that could help catch perpetrators are often left on storage shelves in police stations and labs due to funding shortages. It can cost between $1,200 and $1,500 to test a rape kit.

California is not the first state to address backlogged rape kits statewide. Six other states have passed legislation requiring law enforcement to inventory backlogged kits. Of those states, Texas, Illinois and Colorado also require the tests to be submitted to crime labs within a certain time frame.

In 2003, after New York City processed 17,000 backlogged rape kits, the city's arrest rate for rape went up by 30 percentage points, from 40 percent to 70 percent.

Currently, there are an estimated 400,000 unprocessed rape kits in the United States, according to the sexual assault advocacy group End the Backlog, which lobbies for policies to expedite rape kit processing.  

(Reporting by Jennifer Chaussee in Berkeley, California; Editing by Dan Whitcomb and Eric Beech)