The sheriff's office released a video Friday showing Harrouff calmly walking out of the restaurant moments before police responded to a 911 call of a stabbing attack and arrived to find the teen biting off part of a dead man's face in the driveway of a Tequesta couple's home, officials said. The man's wife was found dead in the garage and a neighbor suffered multiple stab wounds.

Harrouff was taken to a nearby hospital where he remained in an unconscious state. Police and hospital workers have completed some tests, but have not yet found any evidence of drug use.

"He had no criminal record ... he was a good kid," Martin County Sheriff William Snyder told reporters Tuesday, adding that Harrouff had no apparent relationship to his victims and that the attack seemed to be "completely random."

The victims were later identified as John Joseph Stevens, 59, and his wife, Michelle Karen Mishcon, 53. They left behind a daughter, Ivy Stevens.

"There's not one thing in this case that seems to make sense," Snyder added, shaking his head. "We grasp to get our footing and try to understand what happened and why ... but we can't."

What doesn't make sense to police is that Harrouff does not fit the typical description of a deranged murderer. He was a star high school football player and an excellent student, the Miami Herald reported. He took Advanced Placement classes in the International Baccalaureate program at school.