GRAND JUNCTION, Colo. -- A Castle Rock man is accused of having sex with a dog and forcing a 7-year-old boy to watch.

Jason Lee McRoberts, 30, was in court Thursday in Grand Junction, where the alleged incident occurred.

According to a police affidavit obtained by 7NEWS, the boy stayed with the man from August to December 2007. It was during this time that the boy said "Jason" had sex with a male dog named JoJo in the bedroom of a Grand Junction home they shared.

The boy told police that "Jason" instructed him to watch because he should learn how to do it himself.

Mesa County District Attorney Pete Hautzinger said he's never seen anything like the case before.

McRoberts, a former resident of Grand Junction, is under investigation on a felony obscenity charge and posted a $1,000 cash bond after his hearing Thursday. He's also wanted on a Grand Junction police warrant for indecent exposure, according to the police affidavit.

Hautzinger told the Grand Junction Daily Sentinel that it is not clear whether McRoberts will face any child-abuse counts.

The alleged incident came to light in June, when the boy's mother said she caught her son trying to have sex with the family dog and he told her that he had learned how from "Jason." The boy and his mother live in Amarillo, Texas.