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TEQUESTA (CBSMiami) – As the teen dubbed the “Cannibal Killer” remains unable to speak in a hospital bed, his father is opening up about the shocking double murder of a Tequesta couple for the first time on Dr. Phil.

“This is the worst thing I could ever think of, this is the worst nightmare I could ever dream of, what’s happened. I’m deeply sorry for what my son did to those people, and I’m apologizing for him, because Austin would have never knowingly done anything like that. He’s such a good person, he would never knowingly do something like that. I’m truly sorry to those people,” said Dr. Wade Harrouff.

Austin Harrouff’s father left speechless and in tears, opening up for the first time about his son.

The younger Harrouff is accused of stabbing John Stevens and Michelle Mishcon to death in their home – attacking them at random and injuring a Good Samaritan who tried to help.

The sheriff says deputies arrived to find Harrouff biting Stevens’ face – shocking the community and his own family.

“He’s always been the kindest, caring kid I’ve ever seen. He always wanted to help people, he’s always very… I called him the happy boy. The last two weeks he started not being happy. He started being real serious,” Wade Harrouff said.

Officials are still waiting for toxicology results to see if flakka or bath salts were in Harrouff’s system.

His father, a prominent Jupiter dentist, says mental illness – not drugs – is behind the violent attack.

It took multiple deputies, a Taser and a police dog to pull the Florida State University student off Stevens.

The Martin County sheriff says Harrouff was making animal noises when he arrived at the hospital.

Wade Harrouff talked about his son’s bizarre behavior leading up to the murders.

“He grabbed a bottle of Wesson oil and was going to drink it, then she stopped him and he poured it in a bowl and put parmesan cheese on it and ate that,” he said.

Harrouff’s father has said his son’s organs are failing.

You can watch the full interview tomorrow on Dr. Phil starting at 3 p.m. on CBS4.