Updated

Testing of thousands of rape evidence kits that sat ignored for years in Memphis has resulted in the identification of 16 people suspected of raping multiple victims, an investigator said Monday.

Memphis, Houston, Cleveland and Detroit are among the U.S. cities working to reduce a backlog of thousands of untested rape kits, with hopes that evidence collected from the kits could lead to prosecution of more sexual assault cases. Rape victims have sued the city of Memphis, alleging that the failure to test some 12,000 kits has allowed too many rapists to escape prosecution.

In Memphis, the backlog dates back to the 1970s, officials say. After the backlog was revealed in late 2013, Memphis Mayor A C Wharton Jr. formed a task force charged with eliminating it. Police began using test results to start investigations into finding victims and suspects.

A report issued by former U.S. Attorney Veronica Coleman-Davis in June 2014 said no one maliciously or wantonly allowed the kits to remain untested in Memphis. Instead, the report attributed the problem "to a general and collective failure to understand the importance of DNA testing as was reflected in common practices in place locally and nationwide."

Rape kits contain samples of semen, saliva or blood taken from a victim. Specimens containing DNA evidence are uploaded to the FBI's Combined DNA Index System, or CODIS, to check for a match.

During a public meeting about rape kit testing, Memphis police Lt. Cody Wilkerson reported that 5,386 kits have been sent to labs for testing and that 58 cases have been sent to prosecutors for indictment. He said 25 alleged rapists have been identified, including 16 believed to have assaulted multiple people.

Dozens of investigations have been cut short because of statutes of limitations on rape charges, or the deaths of victims or suspects, he said.

Members of women's groups present at the meeting said news of the backlog and the new investigations has led to healthy public discussion about the evils of rape and its effect on victims.

"We're saying the word 'rape' all the time," said Deborah Clubb, executive director of the Memphis Area Women's Council. "We're changing our city."

In February, officials in Houston said evidence from more than 6,600 rape kits that went untested there for years has turned up 850 hits in the FBI's nationwide database of DNA profiles.

In Detroit, prosecutors discovered more than 11,000 rape kits in an abandoned police warehouse in 2009. In Cleveland, prosecutors have sent their entire 4,700-kit backlog for testing.