An evidence bag from a sexual assault case in the biology lab at the Houston Forensic Science Center in Houston. (Pat Sullivan/Associated Press)

THERE ARE 2,369 rape kits sitting on Virginia shelves untested. That’s 2,369 crime victims who, after experiencing the trauma of sexual assault, submitted to an intrusive and painstaking examination designed to collect DNA evidence and identify a perpetrator. It’s an unknown number of rapists who might have been caught but have walked free. It is a failure on the part of Virginia police departments and a symptom of a national epidemic.

Virginia’s untested kits, detailed in a state Department of Forensic Science audit released this month and reported on by The Post’s Rachel Weiner, should have been submitted to the DFS for analysis. But they sat in police departments instead — some since 1988. The state’s newly discovered backlog, which the DFS says it lacks the resources to tackle, is hardly a national outlier: The federal government has estimated that hundreds of thousands of kits languish on evidence shelves across the country. Not testing such kits denies victims closure and lets criminals walk free, ready to do more damage. Cities such as New York and Detroit that have tested backlogged kits have reduced crime rates and identified serial rapists. Yet many states, strapped for lab space and funding, are struggling to work through their backlogs. Others have not even counted or catalogued their untested kits.

There’s some good news. Congress appropriated $41 million last year to a Justice Department competitive grant program in which states may secure funding by detailing their plans for rape kit reform. That means not just working through backlogs but also training officers and prosecutors in the proper procedure for handling cases of rape. This year, the House approved $45 million for the same purpose, and the Senate looks likely to fund the program at last year’s $41 million level, if not higher. Congress’s final budget is also expected to include $117 million for DNA testing and increasing crime lab capacity under the Debbie Smith Act, at least 5 percent of which is supposed to go to backlog reduction. And outside the Beltway, Manhattan District Attorney Cyrus Vance Jr. has offered up to $35 million in funding for jurisdictions nationwide to test kits.

It’s encouraging to see some recognition of the dire need for kit testing. Still, it might take more than funding to get things on the right track. Though Virginia lawmakers were responsible enough to commission the report that counted untested kits, not all states have done the same. Even Virginia has not insisted that the catalogued kits be tested. No national requirement mandates either cataloguing or testing. Funding, both from states and from federal grant programs, will help localities forge through kit backlogs — and bring some rapists to court. But laws with the teeth to make sure kits get off the shelf and into the lab would pave an even clearer path to justice.