A teenager has been accused of killing a Florida couple and biting a victim's face off after in a drug fuelled attack on Monday night.

Austin Kelly Harrouff, 19, hasn’t yet been charged in the death of John Joseph Stevens III, 59, and Michelle Karen Mishcon, 53, in the garage of their home on Southeast Kokomo Lane in Tequesta, Florida, Martin County Sheriff William Snyder said.

Sheriff’s officials were working Tuesday with the local State Attorney’s Office to formally charge Harrouff, who was sedated in a Palm Beach County hospital.

“Although we know a lot about what happened last night,” said Snyder, “there are some things we do not yet know, and there are some things that we will not be able to release just yet.”

Officials got a 911 call about 9:20 p.m. Monday from a man, later determined to be a neighbor who lived across the street from the couple’s home, who said he had been stabbed.

Snyder said: "“He had gotten injured attempting to intervene in the assault that he saw taking place."

The sheriff's deputy arrived to find Harrouff on top of Stevens, who was lying on the driveway leading to the garage. Mishcon was in the garage.

“(The deputy) realized that the offender was actually biting the victim in the face and causing what turned out to be some substantial trauma to his face from bite marks,” Snyder said.

A stun gun did not work on Harrouff. The deputy tried to pull Harrouff off, "but he was exhibiting abnormal levels of strength," Snyder said. Harrouff wasn't wearing a shirt, and Snyder described him as fairly muscular.

Two more deputies arrived within a few minutes and tried to help the deputy who was there.

The Herald:

“Nothing was working,” Snyder said. “They were using all the force that they were able to muster physically.”

A police K-9 was eventually used on Harrouff to get him off Stevens. Authorities were able to remove Harrouff, who sustained a bite from the police K-9.

Snyder said he wouldn’t be surprised if Harrouff had Flakka or bath salts in his system, but officials won’t know for sure until they get toxicology results from the hospital.

According to the National Institute on Drug Abuse, Flakka is a synthetic cathinone drug called alpha-pyrrolidinopentiophenone (alpha-PVP). The institute says it is similar to "bath salts."

"Like other drugs of this type, alpha-PVP can cause a condition called 'excited delirium' that involves hyperstimulation, paranoia, and hallucinations that can lead to violent aggression and self-injury," the institute said on its website.

Harrouff was at dinner with his parents when he became agitated, police later learned.

Harrouff didn’t know the couple, Snyder said, and evidence shows Stevens and Mishcon were randomly attacked while sitting in their open garage.

Amy Lourie, who has lived in the neighborhood since 2003, described the husband and wife as great neighbors who were always having fun and kind to everybody. They would open their garage door and had a television and chairs outside.

“If there was something going on, there would be John and Michelle waving from their garage, watching the game or having fun,” said Lourie. “They hang out in their garage and watch the dogs and talk to the neighbors.”

Michele Antoniewicz, who has lived on the street for 11 years, said there’s a mix of families with children and retirees.

“It’s a really beautiful neighborhood. Quiet,” said Antoniewicz. “People take pride in their homes. We’ve never had an issue at all over here.”

Antoniewicz said she knew Stevens and Mishcon, describing them as “hardworking, good people.”

Before the attack, Snyder said, Harrouff’s parents and fraternity brothers were looking for him.

 woman at the Alpha Delta Phi house on Florida State University's campus said from an upstairs balcony Tuesday that no one named Austin Harrouff is a member of the fraternity. However, multiple photos on Harrouff’s Facebook page show him at the Heritage Grove house, a fraternity and sorority housing complex about a mile from the main campus in Tallahassee.

University officials confirmed Harrouff is a member of the university’s Alpha Delta Phi fraternity. The organization’s president referred questions to its national office in Connecticut.

According to MaxPreps, a high school sports recruiting website, Harrouff played football while in high school in 2014-2015. He was listed as 6 feet tall and 200 pounds.

Harrouff is from Jupiter, according to his Facebook page.

oey Bashwiner, 19, said he attends Florida State University and also went to middle school with Harrouff.

“He seemed like a pretty normal kid,” said Bashwiner. “Nothing wrong, just quiet.”

Bashwiner, who said he is not in the same fraternity as Harrouff, said he would see Harrouff in the gym at the university, and last saw him in early June.

“When I saw it was a kid I went to middle school with, he was in my class, shocking,” Bashwiner said. “You would never expect it.

Harrouff hasn’t had any prior contact with university police, and Snyder said Harrouff doesn’t have a criminal record.

A woman sought by sheriff’s officials Monday night was Stevens’ daughter and Mishcon’s stepdaughter, Snyder said, and she wasn’t harmed.