Authorities Investigating College Student's Deadly Face-Biting Attack On Florida Couple

TEQUESTA, Fla. (CBS) -- Investigators in Florida are still trying to wrap their heads around a gruesome face-biting attack that left a couple dead just outside their home.

CBS Miami reports that 53-year-old Michelle Mishcon and 59-year-old John Stevens III were stabbed and killed Monday night in their garage by a suspect who police have identified as Austin Harrouff, a 19-year-old Florida State University student.

In a press conference, Martin County Sheriff William Snyder explained the chain of events that unfolded the night of the attack.

That evening, Snyder says Harrouff had been out to dinner with his parents but he became upset about something while at the restaurant -- possibly with the service -- and left before the meal was complete.

He then headed north on foot, walking 15 to 30 minutes in the direction of his dad's house. He never made it there. Investigators say Harrouff stopped one block shy and turned left, having the fateful encounter with Mishcon and Stevens shortly thereafter on the 19000 block of Kokomo Lane.

"We may never know why our suspect stops one street short," noted Snyder.

He said neighbors of Mishcon and Stevens described them as quiet and delightful people who enjoyed spending evenings sitting on a couch in their garage.

"We have two middle aged people sitting on their couch enjoying the night and out of nowhere they're attacked by a man with a knife who overcomes them both and kills them. So to say that it's sad somehow misses it. I'm not sure I even have the words to tell you how I feel," said Snyder. "Standing there last night and looking at that scene I was forced to think about the futility of the whole thing, the randomness of it as it began to become clear there was no connections between the victims and the suspect. When we see a connection somehow when it's a domestic no matter how violent it is it's horrific but we draw some constellations in society that they were supposed to be together. But this case they were not supposed to be together. It's a tragedy without words to describe."

One of the neighbors made the 911 call. He too was stabbed trying to intervene and is expected to be okay.

Authorities told CBS Miami that it took several deputies and a K9 to overpower Harouff who arriving officers found lying on top of another man.

"[The arriving deputy] immediately closed the gap between herself and that fight and deployed her Taser. When she got there she realized that the offender was actually biting the victim in the face and causing what turned out to be substantial trauma to his face," Snyder told CBS Miami, adding that Harouff was "exhibiting abnormal levels of strength." He also said his deputies did not try to shoot Harrouff because the angles were too close and they were afraid of hitting the victim.

According to officials, Harrouff did not suffer any stab wounds but the hospital says he is in "grave condition." It's possible he may have ingested something that is causing him intestinal problems.

Several drug tests for cocaine, marijuana and opioids came back negative but other substances including flakka and bath salts have not been ruled out. If he survives, Snyder says his suspicion is that Harrouff will have no recollection of the horrific incident.

He says, back at the restaurant, Harrouff's parents had called police after he left, out of concern for their son. Snyder says they are now overcome with grief over what he did and the possibility they may lose their son.

The autopsy report for Stevens, released Tuesday, revealed he died of multiple serious stab wounds to the head, neck and chest as well as massive blunt force trauma. An autopsy results for Mishcon are expected Wednesday.

The big question -- why a 19-year college student, "who got good grades" and was an active member of a fraternity would do this -- remains unanswered.