A horrific murder took place on D.C.’s Metro on the Fourth of July, when a young man attacked another passenger and stabbed him to death. It had those qualities that make us desperate for an explanation: It was apparently random. It happened in the middle of the day, on a crowded train. It was seemingly entirely unprovoked.

How do we make sense of violence like this?

D.C. police decided to point the finger at synthetic drugs. The Washington Post led with the following: "Authorities suspect that the man charged with fatally stabbing a passenger during a daytime robbery aboard a Metro train Saturday may have been high on synthetic drugs, according to several D.C. police officials with knowledge of the investigation."

"Suspect."

"May have been."

These are weasel words which should not form the foundation of a news report. And indeed, a later news story mentioned that the police were basing this claim entirely on the man’s behavior, not any real evidence.

Police, who have no medical background, have no business driving drug scares by throwing around this kind of irresponsible speculation. Remember the story of the “Causeway cannibal” who attacked a homeless man in Florida and chewed off most of his face? Police speculated that the attacker was high on bath salts, and a barrage of over-the-top headlines followed. In the end, nothing but marijuana was found in his system.

So far, not much information has been made available about the man who was arrested for the Fourth of July Metro murder. He is 18 years old. He had reportedly graduated high school and started college. He had had a series of encounters with law enforcement in the last several months, and his family has said this kind of behavior did not line up with the person they knew.

Perhaps this all points to a dramatic descent into the clutches of synthetic marijuana, which would line up neatly with the police department’s positioning of synthetic drugs as the next big scourge. Or perhaps this young man was experiencing the onset of mental illness. Schizophrenia usually emerges in men in their late teens and early 20s and can lead to violent behavior.

So why go straight to drugs as the cause? Does the desire for a quick explanation with a splashy headline trump any commitment to reporting based on fact?

A follow-up news story described a recent hearing for the suspect on another case, at which his behavior prompted the judge to ask if he had been evaluated for mental competency. If he is not found competent, will that make headlines as the speculation about synthetic drugs did?

Yes, the killing of a man on his way to Fourth of July celebrations was horrific. Yes, the sheer randomness of it is terrifying. But these circumstances do not justify the presentation of unfounded speculation as reality.

Neither the police chief nor the Washington Post should forgo fact by trumpeting the next drug scare.

Megan Farrington is the director of digital communications for the Drug Policy Alliance.

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