Police have arrested a young man after they say he shot and killed his mother inside their Marietta home.Investigators said the shooting happened late Saturday morning in a home off of Tritt Springs Trace.

Shaun Simms, who lives nearby, said the suspect knocked on his door Friday night looking for a place to sleep.

We said We don’t really know you. We would prefer that you went to a neighbor that knew you a little better, maybe they’d be able to help you out, Simms said.

Mario Dorce

Grief stricken family members arrived at the home Saturday as medics worked on the victim in the back of the ambulance.

The woman was later pronounced dead at the hospital.

Suspect was back in the cop car laughing, smiling, joking, um, singing songs and just acting a little crazy, Simms said.

Channel 2’s camera caught a shot of the suspect, Mario Nathaniel Dorce, in the back of a patrol car.

I wouldn’t say it was typical behavior, especially someone that just shot their mother. Um, you would think they would feel sorry for it, or not exactly happy. And that’s what he seemed like, happy, that he accomplished something that he wanted to do for a while, Simms said.

Cobb County police took Dorce to police headquarters for questioning and later charged him with murder.

Dorce is being held in the Cobb County Jail awaiting a first appearance.