A local chiropractor was charged with four counts of murder in the killing of three men and a woman at a North Dakota property management business.

Chad Isaak, 44, a suspect in the slayings at RJR Maintenance and Management in Mandan, near the state capital of Bismarck, was arrested Thursday, according to Mandan police.

Isaak is a well-known chiropractor in Washburn, according to NBC-affiliate station KFYR.

He also lives in Washburn, which is about 35 miles north of the business where the four were found dead Monday, Mandan Police Chief Jason Ziegler said.

Investigators have yet to determine a motive for the killings, but the police chief said Isaak lives on a property managed by RJR Maintenance and Management.

He was charged Friday with four counts of felony murder, burglary, unauthorized entry and unauthorized use of a vehicle. If convicted, he faces a maximum of life without parole for each of the murder counts.

A judge ordered that his bond be set at $1 million. Court records did not show any attorney information for Isaak.

Chad Isaak, left, appears in court April 5, 2019, in Mandan, North Dakota. A judge set a $1 million bond for Isaak who is accused of killing four people, citing the "heinous nature" of the alleged crimes. James MacPherson / AP

The four victims whose bodies were found Monday were the management company's co-owner Robert Fakler, 52, and three employees: Adam Fuehrer, 42, Lois Cobb, 45, and her husband William Cobb, 50.

They died of stab and gunshot wounds, according to a statement from Mandan police.

Officers were able to identify a suspect’s vehicle after watching hours of surveillance video, police said Thursday. Isaak was detained during a traffic stop, and officers conducted a search on his vehicle.

“Evidence discovered on Isaak and in the vehicle provided probable cause to place Isaak under arrest for the murders,” police said.