Former CU Boulder student sentenced to prison and probation for campus sexual assault

A former University of Colorado Boulder student accused of sexually assaulting another student in 2022 was sentenced Tuesday to prison and intensive sex offender probation after his initial sentencing hearing was canceled last year.

Brennan Pieper, 22, pleaded guilty to one count of sexual assault – without consent and was sentenced to 90 days in jail and 10 years of intensive sex offender probation. The sexual assault charge falls under Colorado’s indeterminate sentencing laws for sex offenses, meaning Pieper will have to undergo treatment for sex offenses and seek release.

A jury initially found Pieper guilty of two counts of sexual assault and one count of unlawful sexual conduct in August 2024. It was determined that Pieper’s attorney failed to accurately inform him of a plea offer, according to Shannon Carbone, a spokeswoman for the Boulder County District Attorney’s Office. Pieper had refused a plea deal offered by the prosecutor before the jury trial, Carbone said.

Instead of the case being retried, the prosecutor’s office offered a different plea deal, Carbone said. In July, Pieper pleaded guilty to one count of sexual assault – without consent.

Colorado’s intensive sex offender probation program may include severely restricted activities, daily contact between the sex offender and probation officer, a monitored curfew, home and work visits, drug and alcohol testing, treatment monitoring, and payment of restitution.

If Pieper violates the terms of his probation, he could be sentenced to state prison.

Pieper was arrested on December 2, 2022, on suspicion of a reported sexual assault on CU’s campus in September of that year.

According to an affidavit, a woman reported that she and Pieper were kissing at night in a UC campus dorm when he suggested they go to Kittredge Field. Pieper led the woman to a dark corner of the lot near a shed, held her down and forced her into oral and digital penetration, the affidavit states. The woman told police the incident on the field was not consensual and that she told Pieper “no” several times.

Pieper initially denied being on the grounds, the affidavit states, but when shown surveillance camera footage, he said he and the woman had only kissed.

According to the affidavit, “Pieper changed his story again” and said it was the woman who initiated the sexual contact.

Pieper turned himself in on August 11 to begin serving his prison sentence. Pieper received credit for time served and is scheduled to be released Oct. 17, according to Carbone.

Pieper’s first defense attorney is under investigation for his conduct in the case, according to the prosecutor’s office.

Originally published: October 8, 2025 at 11:19 a.m. MDT