A man has been charged with killing a southwestern Michigan couple, nearly three years after the victims were found in their home.

Keith Lintz of Niles is charged with first-degree murder and a gun crime. Authorities say Carolyn and John Tarwacki were beaten, stabbed and shot in February 2010. They lived in the Niles area, 60 miles southwest of Kalamazoo.

The Michigan State Police launched an investigation and worked with Niles City Police officers, Cass County Sheriff’s deputies, Berrien County Sheriff’s deputies, and Michigan Attorney General special investigators to solve the couple's deaths.  Throughout the course of the investigation, nearly 800 tips were received and over 300 witnesses were interviewed. 

A statement Thursday by the attorney general's office doesn't indicate how police turned their investigation to the 28-year-old Lintz, who was arrested Wednesday. It wasn't immediately known if he has an attorney. He is facing up to life in prison.

The victims worked at a music company in Stevensville, supplying and maintaining instruments for music educators throughout Berrien and Cass counties.