BOULDER, Colo. -- A former University of Colorado student accused of choking and fondling a woman while she was in her car and then taking off his clothes and running away pleaded guilty to the attack, which a judge called "horrific."

Ryan Disselhorst will be sentenced in January after pleading guilty Friday to felony menacing, third-degree assault and second-degree criminal trespassing.

Police said the 20-year-old sophomore assaulted the woman after he and another man ran in front of her car near an intersection, prompting her to stop her car and ask if they wanted to get killed.

That's when Disselhorst reached in the woman's open driver-side window, grabbed her chest, and threatened her, police said. When she tried to call police, he threw her cell phone to the ground, choked her and then dragged her out of the vehicle, police said.

Police said Disselhorst shoved her face in his crotch, and when other drivers came over to help, he stripped off his tie-dye shirt and khaki shorts and ran off.

The victim, also a CU student, later told police she thought she was going die as Disselhorst was choking her.

Boulder District Court Judge James Klein described the attack as "incredibly violent," according to the Boulder Daily Camera.

Disselhorst has since been expelled from school. He told police he only remembers going to a party after leaving work that night.

Disselhorst, an Illinois native, was granted permission to leave the state for the holidays but must return for a Jan. 16 sentencing hearing in Boulder.

The attack occurred at 15th Street and Broadway at about 2 a.m. on May 29.