BOULDER, Colo. -- Boulder police have arrested a registered sex offender accused of sexually assaulting a 14-year-old girl.
Police said Christopher Ehlebracht, 29, was arrested Monday on a warrant alleging sexual assault on a child, enticement of a child and contributing to the delinquency of a minor.
Investigators said Ehlebracht met the teen girl through an online app called Whisper.
The victim told police that Ehlebracht picked her up at her home in Westminster and drove her to his home in Boulder, where he sexually assaulted her.
Ehlebracht was convicted in 2011 of attempted sex assault on a child in Westminster.
Ehlebracht is listed in the Colorado Bureau of Investigation's sex offender registry. That registry can be searched by location and/or name.
App used to lure teen
Lead investigator Michael Harris with the Jefferson County Child Sex Offender Unit also known as "Cheezo" said anonymous apps like Whisper are often used as feeding ground for predators.
"You don't know who you're talking to, it could be your worst nightmare," said Harris. "When kids frequent these apps so do people that desire children for sex.
Harris and his team go undercover on these apps to catch predators before they find child victims.
"Basically all we do is apps now," he said. "Because that's where it's all at."
Whisper allows users to share their secrets with anyone in the world anonymously.
The app is free and available for download on both Android and iPhone devices.
"If there's a way to do something illegally these are some of the ways to do it," said Harris. "It can become very, very sexual."
Whisper allows users to love, chat or ask others users to join a group based on their latest post.
"We as parents need to be on top of all these different apps and they're changing constantly," further explained Harris.
He said what's most concerning about Whisper is it requires users to share their location which allows others to search for nearby posts, that can be less than a mile away.
"When you're allowing someone to see exactly your exact location it's like opening the front door to your house and leaving it open for anyone to enter," said Harris.
Harris encouraged parents to put parental controls on their children's phones. The controls require parental approval before a child can download any new apps on their phone.