Treaver L. Dobberstein, 23, Waupaca, was charged with sexual assault of a child.
Waupaca police were contacted about a possible sexual assault on Feb. 22.
A Waupaca woman told police that Dobberstein had been seeing a 15-year-old girl.
When police interviewed the girl on March 1, she said Dobberstein was her brother’s friend and that she and Dobberstein had sex once at a friend’s apartment on North Main Street in Waupaca.
Dobberstein faces up to 40 years in prison if convicted of second-degree sexual assault of a child.