A Casper man is heading to prison for sexually assaulting a young girl, although he maintains his innocence.

Twenty-five year old Nathaniel Lucas was sentenced to eleven-to-thirteen years in prison, after entering an Alford plea to one count of third degree sexual assault of a minor.

Prosecutors say sometime last year, Lucas was with a sixteen-year old runaway and threatened to blow up her house, if she didn’t sleep with him.

Investigators later searched an empty house in north Casper, where they found used condoms, which were linked to Lucas through DNA testing.

An Alford plea is not an admission of guilt, but it acknowledges that there is enough evidence for a conviction.