"Logan was a good boy we never had any trouble," Suter's grandmother Lurene Benson said. "If he gets angry he goes to his room till he cools off. This time Chris followed him to his room."
Police say 33-year-old Christopher Lancaster died from a shotgun blast to his abdomen.
The shooting happened at the family home on Fairfield Circle late Sunday night.
Dunn Police Chief B.P. Jones says Lancaster and his stepson did not get along.
"They had an argument," Jones said. "The boy got up and went to his room and I understand Mr. Lancaster got up to go back there to the room I supposed to go back to the room to talk to him, but the boy took it as some kind of threat and shot him."
Benson says her grandson had stopped taking his medication for a bipolar disorder, but said his mother was trying to get him back on the medication.
Suter, a student at South Johnston High School had been living in Dunn with his mother and stepfather since April.
Neighbors say the family hadn't lived on Fairfield Circle that long, but seemed like nice people.
Jones says he can't remember a case of domestic violence there this tragic.
"Because there was no premeditation, we had to charge him with second degree," Jones said.
Suter is currently in jail under $150,000 bond.