"I didn't kill her. I killed the demon inside her," Brea, 31, told New York's Daily News in a prison-ward interview at Bellevue Hospital, where he is being psychiatrically evaluated.
Brea said he heard voices, including that of God, instructing him to attack his mother Yannick, 55. He confronted her late Monday night in the Brooklyn apartment they shared together.
"She had the voice of the demon," Brea said. "I asked, 'Do you believe in God?' She said, 'No, Michael no,' and began screaming. I began slashing her like this," he said, making violent hacking motions with his right hand.
He added: "I didn't want to kill her right away. I wanted to give her time to get right with God," he said.
The police arrived, but Brea says he knew he had time to finish the job. "I knew they wouldn't open the door and stop me because the spirits were protecting me," he said. "I just kept cutting her. No one could stop me. I was doing the work of God."
Brea has been charged with second-degree murder and criminal possession of a weapon.