Before Austin Harrouff was arrested and charged with the fatal stabbings and infamous face-biting of a Martin County, Florida, couple in their home in August, he gave a bedside interview with the "Dr. Phil" TV show.

The sheriff’s office said there’s no legal way it could have prohibited the interview, but the son of the man killed by Harrouff told The Post in an exclusive interview that the sheriff could have arrested the Jupiter teenager sooner.

In a segment called “The frat boy dubbed ‘cannibal killer’ breaks his silence from his hospital bed,” the show programmers say they have “an exclusive interview, right before his arrest” that is set to air Friday.

“Harrouff speaks out for the first time from his hospital bed,” the preview reads. “What does he say caused him to go from popular student to an accused killer?”

There was neither a promotional video to tease the story nor photos on the show’s website. The show’s staff only provided a blurb for the upcoming program and made no other comment

Martin County Sheriff William Snyder told The Post on Monday night that his department was aware of the phone interview, conducted a few days before Harrouff's arrest Oct. 3, but there was nothing it could legally have done to stop it even if he was arrested. He said his office can't bar anyone from speaking with the media who wishes to do so.

“We were surprised,” Snyder said of the interview.

John Stevens IV, the son of John Stevens, whom Harrouff is charged with killing, said if the sheriff’s office had arrested him sooner, there may have not even been the opportunity to give an interview.

“It may be his right to give a phone interview, but if the process would have been followed like any other double murderer (and he was arrested immediately), he may have not been so inclined to give an interview from jail,” Stevens told The Post.

On Aug. 15, the Martin County Sheriff's Office says, Harrouff beat Stevens, 59, and Michelle Mishcon, 53 to death at their home on Southeast Kokomo Lane after he stormed out of a Duffy's Sports Grill in Jupiter where he was with his father. A neighbor tried to intervene and was injured in the process, according to authorities.

Investigators say it’s unclear if Harrouff was under the influence of drugs, but when authorities arrived, he was biting Stevens’ face. While in the hospital, his organs began to fail, and the hospital staff said it believes he drank some cleaning fluids from inside the garage where he killed the couple.

Austin Harrouff is being held at the Martin County Jail on two counts of second-degree murder with a weapon, one count of attempted first-degree murder with a weapon, and one count of burglary of a dwelling with assault or battery. The state plans to pursue first-degree murder charges, which must be presented to a grand jury.

John Stevens IV said even before the 19-year-old Harrouff was taken to the hospital after the slayings, he had the benefit of white privilege on his side. He said if anyone else in any other place had done this type of crime, they would have been arrested right away.

“I’ve never seen a black or minority suspect with such an inherent sympathetic spin (as Harrouff is getting),” he said. “They make him seem as sympathetic as possible because he’s privileged and white, and it’s really, really sad.”

He said when Austin Harrouff's father, Wade, went on "Dr. Phil" several weeks ago, it was another ploy for more sympathy. In a segment that aired Sept. 7, Harrouff told Dr. Phil that his son suffered from undiagnosed mental illness and apologized for his son's actions.

When The Post attempted to get comment from Wade Harrouff on Monday evening, he said could not speak at this time.

Stevens said much of the coverage by news outlets has focused on how Harrouff was a good student at Suncoast High School and Florida State and popular, painting him as a victim. What people forget, Stevens said, is two people were killed and others hurt Aug. 15.

“We all live in a time when we’re cynical about media and law enforcement,” he said. “My reaction is general disgust.”

“I really hope people can use their brains and see that (Harrouff) is a monster,” Stevens said.