Authorities said Tuesday that the bodies of a man and woman found in the home they shared northwest of Duluth died of a murder-suicide.

The bodies of Loretta J. Billman, 62, and Robert E. Kerr, 55, were discovered Monday on sprawling residential property near Saginaw, the St. Louis County Sheriff’s Office said Monday.

Sheriff’s Sgt. Wade Rasch said investigators know which of the two fired the fatal shots, but “I’m not putting that out at this time.”

Rasch also did not address a motive for the killings.

Relatives of the couple and their co-workers made the discovery in the home and called 911 after the two failed to report for work, the Sheriff’s Office said.

The couple lived on a large tract of rural land valued at $775,000 and includes a 8,400-square-foot home owned by Billman, according to county property records.