Just before midnight Tuesday morning in St. Petersburg, Florida, 37-year-old Jolene Andrews and her boyfriend, 47-year-old Alton Pyles, heard a window on the house get smashed. They went outside to investigate, but went back inside when they saw a man dressed in all-black tactical gear and a ski mask on. Just as they tried to close the door, the intruder forced his way in.

The masked man immediately grabbed Jolene and forced her to the ground at gunpoint. At this point, Alton yelled for help. 18-year-old Malachi Heisler (above, left) heard the cries and went to investigate.

“Just by the sound of the person’s voice, it was distress,” Malachi said. “And I knew it wasn’t a joke.”

He made his way toward the cries, and there he saw the mysterious intruder with a gun to his mother’s head. Malachi grabbed a rifle.

The gunman then turned the gun toward him. It was at that time that Malachi let off a single round, striking the man in the upper body, killing him.

Then reality hit the teen. He recognized the tattoos on the man’s arms – it was his estranged father – 46-year-old John Heisler (above, right). He was now dead.

He told a local news station that he always feared his father would come back.

“It’s not something you prepare for,” he said. But he had a feeling this was the type of thing his dad might do some day.

“He wasn’t a good dad. I’ll say that,” Malachi said.

Jolene Andrews had obtained a restraining order against John Heisler back in May of this year due to domestic violence. It barred him from her home, either of the kids’ schools, and her workplace.

No charges have been filed in the case, as investigators deemed Malachi Heisler’s actions justified.