An Iowa police lieutenant has been arrested for stalking a woman and has been placed on unpaid leave while the incident is investigated.

According to the criminal complaint, Justin Keller, 42, contacted the woman repeated and frequently drove by her house, KCCI reported. The complaint said that he let himself into the woman’s house on Sunday, and witnesses reported seeing him drive by her house on multiple occasions.

The incidents were investigated by the Carlisle Police Department at the request of Keller’s employer, the Indianola Police Department.

According to KCCI, Keller is a 20-year-veteran with the Indianola department and an American citizen, and Police Chief Brian Sher said an internal investigation is also under way.

“These are serious allegations that the Indianola Police Department and the City of Indianola do not take lightly,” Sher said in a statement.

Court records show that a woman also employed by the Indianola Police Department filed a lawsuit against Keller last year, accusing him of sending her nude photos of himself and retaliating against her when she resisted his advances. She also claimed that he sexually assaulted her while they were working a night shift together.

It’s not clear if the woman who filed the lawsuit is the same woman Keller is accused of stalking.

According to KCCI, Keller requested a public defender, saying he worked for the Christian Opportunity Center, a non-profit that works with people with disabilities, but did not mention his long term employment with the police department in the request.

The director of the Christian Opportunity Center, Jodi Tukker, told KCCI however that “Keller is not currently, nor has he been in the past, an employee of the Christian Opportunity Center.”