Easier collected than analysed (Image:Ted Soqui/Corbis)

NO ONE knows the exact figures, but across the US, tens of thousands of rape test kits are thought to be lying around awaiting analysis. The country is finally starting to clear this backlog of DNA evidence from police investigations, some of which dates back decades. But simply spending more money on testing won’t prevent history repeating itself. Poor training and attitudes on the part of investigators will also need tackling.

The use of DNA evidence in solving crimes took off in the 90s, when forensic scientists and many labs found themselves suddenly inundated with samples to test. In an effort to deal with the backlogs that built up, the federal government provided extra funding via the Debbie Smith Act in 2004. Even so, in 2009, a police storage facility in Detroit, Michigan, was found to be holding 11,000 untested rape kits. In 2013, the city of Memphis, Tennessee, admitted it had a backlog of 12,000.

It is unclear how many rapists may be walking free as a result, although since Houston, Texas, launched an effort to clear its backlog in 2013, 29 people have been charged. Last month, Houston officials announced that 850 DNA samples in the backlog – originally more than 6500 kits – had been matched to the FBI’s DNA database, a possible method for spotting crimes such as serial rapes. Conversely, DNA testing also has the potential to exonerate innocent suspects.


Memphis has launched a $6.5 million project to have its backlogged evidence processed by a private lab. But funding was only ever part of the problem. A lack of communication between investigators and forensic scientists can also prove problematic, says Richard Pinchin at the Forensic Knowledge Partnership in Reigate, UK, who has advised US law enforcement agencies on how to tackle the unprocessed evidence.

In the UK, police forces send DNA evidence to private labs, which can be paid extra to turn around results within a day. To stick to budgets, investigators are more likely to select only the most relevant samples for analysis, says Pinchin. “That doesn’t happen in the US,” he says. US police forces mostly have their own labs, so tend to send all their samples for testing. This can lead to labs being overloaded with irrelevant material to process, creating backlogs.

“I remember when prosecutors used to ask us to test everything,” says Mitch Morrissey, district attorney of Denver, Colorado. “That is ridiculous.” He is retraining his investigators to be more selective in their DNA testing.

Another crucial aspect of police retraining has been to change investigators’ attitudes towards people who report being raped. “The victim of rape is not always believed, but studies show that false accusations of rape are no greater than for any other crime,” says Pinchin.

Studies suggest that victims are less likely to be believed if they have been drinking, for example, while local policing policies may require officers to be absolutely certain a rape has taken place before sending a test kit for analysis. Both scenarios could help explain why so many DNA samples are collected, only to end up sitting in a warehouse.

This article appeared in print under the headline “US mired in DNA testing backlog”