A horrific and random murder in Florida, in which a 19-year-old man stabbed two strangers to death and tried to eat the face of one of them, has the media once again warning about the "zombie drug" flakka. The synthetic stimulant has been implicated in previous bizarre and violent incidents, most notably the 2012 attack on a homeless man in Miami in which the assailant was also found biting his victim's face. But despite widespread reporting on this attack as drug-induced, toxicology tests found no trace of synthetic stimulants in the attacker's body—something to keep in mind as we approach this latest attack.

In this case, the young man, Ausin Harrouff, was a student at Florida State University with no criminal record and no relationship to his victims. On Monday night, he abruptly got up from having dinner at a sports bar with his parents, entered the nearby garage of Michelle and John Stevens, and stabbed the married couple to death. A neighbor who tried to come to the Stevens' rescue was also stabbed but is expected to survive. When police arrived on the scene, they found Harrouff "grunting" and gnawing on Mr. Stevens' face.

Harrouff tested negative for cocaine, meth, marijuana, and opiates. But Martin County Sheriff William Snyder told reporters that Harrouff may been on the synthetic drugs known as flakka or bath salts. "We will be doing sampling of his blood to see if there was flakka or bath salts, which are known to cause what we call the excited delirium, and he did have some indications that we might be working with that," Snyder said.

Results of toxicology tests for those substance are still pending, yet there's reason to suspect they'll come back negative. For one thing, police report that Harrouff did not have the elevated body temperature typically associated with flakka use. He was also quite lucid, according to the intervening neighbor, which also betrays a lack of drug-induced psychosis.

Still, the media is running with the "zombie drug" story. Think they'll all issue updates if the toxicology tests come back negative?