Boulder County, Colo. - The Boulder County Sheriff’s Office was notified by Longmont Public Safety that they were investigating one of our deputies about an incident that took place last night at a home in Longmont.

After investigating, Longmont Public Safety issued an arrest warrant for Peter Markusen on the charges of 3rd Degree Assault (M1), Harassment (M1), Domestic Violence (M1), and Child Abuse (M2). Markusen was arrested on January 27, 2026, at the Boulder County Jail after turning himself in.

“We take allegations of domestic violence very seriously. While this incident occurred outside our jurisdiction and is being investigated by another agency, we are taking our own appropriate administrative actions, as we hold our deputies to a higher standard of conduct,” said Sheriff Curtis Johnson.

The Boulder County Sheriff’s Office has placed Markusen on unpaid administrative leave per office policy.

Markusen has been employed by the Boulder County Sheriff’s Office since 2019.

We are committed to transparency and accountability. If an employee is arrested, we work proactively to share information in a timely manner, whenever possible.

As in every criminal case, these charges are an accusation, and the defendant is presumed innocent unless or until proven guilty.

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/s/ Carrie Haverfield, Sr. Communications Specialist