DENVER (AP) -- Colorado police departments are collecting hundreds of rape kits, but many of those are not being tested.

According to KMGH-TV, authorities said hundreds of rape kits remain untested on shelves.

Since 2008, the Denver Police Department has received more than 1,000 rape kits, but 44 percent of those kits have never been tested.

Since 2007, Fort Collins authorities have collected more than 240 rape kits, but 72 percent of those rape kits were not tested.

Some police departments say they don't want to overwhelm police laboratories with evidence that may not result in an arrest.

The kits are used to identify rapists by gathering DNA to use in prosecution and send to a national database.