An 18-year-old Austin man has pleaded guilty to one count of third-degree criminal sexual conduct involving a victim 13 to 15 years old.

Kai Backous previously pleaded not guilty to two counts of third-degree criminal sexual conduct last November. He pleaded guilty Monday as part of a plea agreement.

According to a court complaint, the victim’s father reported Backous last month after he found online messages between the 18-year-old and the victim. The victim told police she allegedly slept with Backous on two separate occasions in October at his apartment near Riverland Community College, where she allegedly stayed overnight during one occasion.

Backous denied having sex with the victim and said he knew the victim was middle school-aged, according to the complaint. He told police he only hung out with the victim and one of her friends once, and she once came to his apartment to watch a movie before the victim went to a friend’s house.

Backous will be sentenced in May.