Charles Niemi, a 65-year-old martial arts instructor in Centennial, was arrested Thursday for sexually assaulting one of his young students, the Douglas County Sheriff’s Office said.

Niemi is facing two counts of sexual assault on a child, pattern of abuse.

The assault happened around a year ago while the alleged victim was one of Niemi’s students, officials said. Niemi currently works as an instructor at Centennial’s Spirit Warrior Martial Arts on East County Line Road.

Officials said they believe Niemi may have additional victims.

Anyone who may have information about the case, or who believes they or someone they know might be a victim of Niemi, is asked to contact Detective Ducat at 303-814-7179.

Niemi is currently being held without bond at the Douglas County Detention Facility.