TULSA, Oklahoma - Tulsa Police took a man into custody after the death of his grandmother in north Tulsa early Tuesday.

He has been identified as 35-year-old Antoine Jermaine Jackson.

They don't know why he killed her, other than he told officers he had been smoking water, which is a term for PCP.

Firefighters and paramedics say Jackson was in the house in the 3200 block of North Wheeling Place when they arrived just before 2 a.m. They told police he began acting strangely and was belligerent, then ran away.

Police say 78-year-old Arlevia Jackson was found inside her home, dead from trauma with large amounts of blood all around her head and chest. They say there was no gunshot wound, but it looks like she was beaten to death.

Antoine Jackson, said he had killed his grandma. He was arrested and booked for first degree murder.

"He had blood on him, made some statements there that were inconsistent with what we saw and there was enough probable cause to arrest him. Plus, his behavior at the scene was violent," said Sergeant Dave Walker, Tulsa Police Department.

Police say the incidents of a son killing a mother is less than two percent of all murders and the number of grandson killing grandmothers is even less than that, yet Tulsa has had two cases of matricide in recent months and now this. It's quite unusual.

He says all murders are tragic, but these somehow feel worse.

"This is just another of those but is exacerbated because the victim is elderly and did not pose any type of threat to the suspect," Walker said.

Police say the victim had never had any contact with police in her life. They say they have had contact with the grandson before but didn't say why.

A friend of the victim said Arlevia was a quiet woman who didn't talk much but was very kind and sweet and had been a widow for many years. She couldn't imagine why anyone would want to hurt her.