Student 'bites dead man's face after stabbing couple to death'

A student was allegedly found biting a dead man's face after stabbing a couple to death at random, police said.

Austin Harrouff, 19, may have been on a hallucinogenic drug when he is said to have attacked John Stevens and Michelle Mishcon outside their Florida home, police said.

A neighbour was badly injured after trying to intervene, before calling 911 at 9:20pm on Monday night.

Harrouff had joined his family for dinner at a nearby restaurant but he stormed off, apparently agitated about slow service, the sheriff said.

His parents said they called police and some of his fraternity brothers in an attempt to find him before the alleged attack.

About 45 minutes later, he apparently targeted the couple at random, the sheriff said.

Martin County Sheriff William Snyder said: "The suspect in this case was abnormally strong. So getting that excited delirium type increased adrenaline strength.

"Somebody not feeling pain, not responding to a dog bite, repeated stuns from a Taser, taking three to four deputies and officer dog to get him off. That’s somebody with a lot more strength than you would normally encounter."

Authorities think he may have been on "flakka", a synthetic drug which has been linked to paranoia and hallucinations.

The suspect is being held under guard at a hospital and has not been formally charged.

The Sheriff said on Tuesday his condition has deteriorated significantly and he may not survive.