The Hennepin County prosecutors have filed second-degree murder charges against a 20-year-old man who police say killed a good Samaritan on Friday.

Thomas Sonnenberg, 69, let Devon Parker into his north Minneapolis house shortly before noon after Parker pleaded for refuge, saying people were chasing him with a bat. Prosecutors say Parker, of Minneapolis, then grabbed Sonnenberg's gun off his hip and shot him in the head.

"This is a good Samaritan who is doing what we always hope people will do, help others," Hennepin County Attorney Mike Freeman said Monday. "If we don't have that kind of cooperation and assistance, we lose something in our society."

Freeman said more charges against Parker could be forthcoming.

Sonnenberg let Parker into the house on the 3700 block of Aldrich Ave. North and locked the door, according to the criminal complaint. The two men were in the kitchen when Sonnenberg dialed 911. Parker was shouting erroneous addresses while Sonnenberg was on the phone with 911 operators, Freeman said.

Sonnenberg's wife later told police that she heard Parker ask for a weapon and then heard a gunshot. She said Parker came out of the kitchen and ordered her on the floor, choked her and held her husband's gun to her head.

When police arrived about five minutes after the 911 call, an officer looked through a window and saw Thomas Sonnenberg slumped over in a kitchen chair, police said.

Sonnenberg's wife told the officer that the lock couldn't be opened from inside without a key. Through the window, the officer ordered Parker to the floor at gunpoint, and Sonnenberg's wife unlocked the door for police.

The Associated Press reports that Sonnenberg's wife is recovering from her injuries at a family member's house.

In a report released Monday, the Hennepin County Medical Examiner listed Sonnenberg's cause of death as a gunshot wound to the head.

Parker was previously convicted of assault and shooting at a public bus. He was scheduled to appear last Friday to be sentenced in the assault case.

Parker is being held in Hennepin County Jail on $2 million bail. His first court appearance is set for Tuesday.