Police are accusing a 19-year-old of killing a 21-year-old who intervened during a fight Friday in St. Paul.

19-year-old Theotis Antonio Thomas is being charged with one felony count of second-degree murder in connection to the death of the 21-year-old.

The criminal complaint states Thomas got into a physical dispute with his girlfriend and put his hands around her neck. The 21-year-old then stepped in, grabbed Thomas and slammed him on a bed. Thomas got upset, left and is accused of saying he was going to return with a gun, police said.

The complaint says Thomas returned later on and shot the 21-year-old in the head.

Police identify the victim as 21-year-old Mark Franklin Jr.    

Franklin died of a gunshot wound at Regions Hospital on Friday. Police responded to a 911 call early Friday about shots fired inside a home.    

Police say people in the house reported being there when Franklin was shot and that someone drove him to the hospital.    

Officers found two shell casings in the bedroom and what appeared to be a bullet hole in a bedroom wall. They also recovered a .380 caliber handgun in a vehicle Thomas frequently drives.

Thomas turned himself in to police headquarters late Friday.