GOLDEN, Colo. -- A former teacher and tennis coach was sentenced to 11 years to life in prison Tuesday for having a sexual relationship with a former student.

A Jefferson County jury convicted 36-year-old Kevin Ponis in January on one count of sexual assault on a child by a person in a position of trust -- in a pattern of conduct.

Prosecutors said he had sex with a 17-year-old girl during the summer following her graduation from Dakota Ridge High School in Littleton. Ponis has said he thought the girl was 18 at the time.

In a jailhouse interview, Ponis said he was upset and disappointed that he made decisions that brought him down and acknowledged he "wasn't thinking" when the relationship was taking place.

Prosecutors argued during Ponis' trial that he had access to athletic and school rosters, and could have learned the younger student's age if he wanted to.

Two other students testified they also had sexual relationships with Ponis, but they were 18 at the time, so he did not break the law in those cases.

"They were getting together with each other and realizing that they weren't the only one, they weren't special, that he's a fake. He's not what we all thought he was," said Ali Lecoq, the victim's friend.

Ponis asked to be out on bail while his attorneys appeal his conviction but the judge turned down his request.

"He has demonstrated his very narcissistic view of the world, and that is, he thinks of things simply through his own pleasure, and I'm sure he's not lookly very fondly at the prospect of going to prison," said prosecuting attorney Steve Jenson.

Ponis' conduct in prison will determine exactly how long he will remain there.