Butler police are investigating the death of a 41-year-old man Thursday night at his home on the 300 block of First Street.

Matthias J. Johnson was found unresponsive in his bedroom about 11:45 p.m., authorities said. Foul play is not suspected, said police Deputy Chief David Adam.

An autopsy was planned for 4 p.m. Friday but a cause of death would likely remain unknown until toxicology reports are completed, according to Butler County Deputy Coroner Larry Barr.

There was no sign of trauma or other injury on the body, said Barr, who pronounced Johnson dead at the scene about 12:30 a.m. Friday,

Police said Johnson's 43-year-old girlfriend called 911 after awakening and finding him partially on the bed and floor.

Paramedics performed cardiopulmonary resuscitation for about 10 minutes but to no avail. They checked with a physician at Butler Memorial Hospital before discontinuing resuscitative efforts.