CNN —  

A person of interest has been detained as part of the investigation into four deaths at the RJR Maintenance & Management office in Mandan, North Dakota, a release from the Mandan Police Department says.

The bodies of three men and one woman were found around 7:30 a.m. on Monday and were identified as owner Robert Faklar, 52, and employees Adam Fuehrer, 42, Lois Cobb, 45, and William Cobb, 50, police said on Tuesday. Two of the victims were husband and wife.

Police have not said how they died and no weapons were recovered at the scene.

The person of interest was detained today after the investigation led officials to Washburn, North Dakota, according to Thursday’s release.

Evidence from the crime scene has been sent for analysis and police are looking at videos of the surrounding area, Mandan Police Chief Jason Ziegler said earlier this week.

RJR, which is a property maintenance and management company, has posted several short statements on Facebook saying they were closed Monday and Tuesday.

“We will be spending this time discussing our process to move forward and grieve the great losses,” the company said.

The company said they will be holding a news conference on Friday.