Austin Harrouff
Austin Harrouff has been charged with two counts of second degree murder Martin County Sheriff's Office

A Florida State University student accused of murdering a couple and chewing on a victim's face will not be put to death if he's convicted of his alleged crimes.

Despite the wishes of the victims' families, the state is not pursuing the death penalty against Austin Harrouff, 20, who faces a string of charges, including two counts of first-degree murder with a weapon.

"After careful review of the case and applying the statute that controls the seeking of the death penalty, it was decided to not seek it," Jeff Hendriks, the assistant state attorney who is prosecuting the case, said this week.

Harrouff, a Florida resident, is accused of stabbing John Stevens III, 59, and Michelle Mishcon, 53, to death at their home in Jupiter in August of last year.

Police say he was found biting Steven's face, leading them to initially believe he was under the influence of a drug known as flakka.

Harrouff told a deputy that he "ate humans," with detectives saying they recovered what appeared to be human flesh from Harrouff's teeth.

It's not clear if Harrouff's lawyers will be seeking an insanity defence.

In an interview on US TV show Dr Phil, Harrouff said he started hearing voices from a young age, which continued into his late teens.

"At college, I heard voices of monsters and stuff. I never realised that I was hearing voices that weren't there ... people tell me things, like them telling me to run," he said, denying ever intentionally taking flakka.

Harrouff apologised and said he "never meant for this to happen ... I wasn't conscious of what was happening to me". He said he didn't know the couple he is alleged to have murdered.

His father, Wade Harrouff, said his son "started getting weird" two weeks before the attack and believes he suffered a psychotic episode.

He said on the day of the killings, 15 August, he was having dinner with his son before he abruptly left and walked to his mother's house two miles away, where he tried to drink cooking oil.

His mother took him back to the restaurant, Wade Harrouff said.

"I grabbed him by the shirt [and said] 'what is wrong with you?' Then he left ... I got a call about two in the morning. Police said 'we've found Austin ... he's killed two people and eaten them.'"

Harrouff remains at Martin County Jail without bail. A date for his trial has not yet been set.