Police charged 22-year-old Jesus Trevino with murder Saturday in the fatal shooting of 13-year-old Isiah Cantu.
Cantu died Friday night after being shot in the head outside a north side apartment.
Trevino was taken from the scene and questioned by officers, investigators said.
Police said he was arrested on a theft warrant and then confessed to shooting the teen.
According to police, Cantu and his step-brother were outside an apartment in the 500 block of Everest Street when they were approached by a suspect around 8:30 p.m.
The step-brother told police he was hit in the back of the head and fell to the ground. He said he heard one gun shot, police said.
EMS transported Cantu to University Hospital, where he died shortly after 10 p.m. Friday.
Witnesses alerted police to the location of the alleged murder weapon. A gun was found only a short distance away from where the shooting took place, police said.
Police said they were initially looking for two suspects, but they now believe Trevino acted alone.
Investigators are trying to determine whether Friday’s shooting is connected to another shooting that occurred on the north side on March 9.