Proceeding without the benefit of a plea agreement, a Duluth teacher admitted Friday to sexually assaulting a 15-year-old former student.

Karla Jean Winterfeld, 33, pleaded guilty in State District Court to a felony charge of first-degree criminal sexual conduct, acknowledging that she engaged in multiple sex acts with the victim over the course of about two weeks in May.

Judge David Johnson told the one-time Lincoln Park Middle School teacher that she is facing a presumptive prison sentence. Winterfeld said she understood the consequences and the rights she was waiving in entering the plea.

Minnesota sentencing guidelines call for a presumptive 12-year sentence for a defendant with no criminal history who is convicted of first-degree criminal sexual conduct. Winterfeld's attorney, however, can file a motion seeking a shorter prison term or probation.

Winterfeld cried throughout the plea hearing, which lasted only about five minutes. In establishing the factual basis, she was asked to testify only vaguely about her relationship with the victim.

"We engaged in sexual penetration," she acknowledged.

Winterfeld was arrested May 21 by Duluth police. A criminal complaint states that she admitted to sexual activity with the victim several times between May 4-19. Police said they also recovered video recordings, photographs, text messages and other evidence supporting the allegations.

At the time of her arrest, Winterfeld was teaching at both Lincoln Park and in a combined position at the Duluth Area Learning Center and Academic Excellence Online in the Historic Old Central High School building. She started at Morgan Park Middle School in 2007.

Winterfeld in June was placed on unpaid administrative leave "pending final disciplinary outcomes up to and including termination" after the Duluth School Board unanimously approved a letter of discipline. The final disciplinary outcomes and letter are not currently public information due to privacy laws since Winterfeld has decided to appeal the proposed discipline.

Johnson scheduled sentencing for Nov. 16. Winterfeld remains on a $100,000 bond.

Outside the courtroom, defense attorney Jacob Brodin and St. Louis County prosecutor Jon Holets said they would reserve comment until sentencing.

"It went as expected," Holets said of Friday's hearing.