When a grand jury decided late last month not to indict the two police officers involved in the fatal shooting of Tamir Rice, the 12-year-old whose killing outside a Cleveland recreation center became a cause célèbre of the Black Lives Matter movement, the task of announcing the verdict fell to the Cuyahoga County prosecutor Timothy J. McGinty. McGinty, who is in the midst of a heated Democratic primary race, appeared decidedly unhappy to be handling the case. When he presented himself to the TV cameras on Dec. 28, he shifted from foot to foot and often looked fixedly at his prepared statement. He said he told Rice’s mother that what happened to her son was ‘‘undeniably tragic.’’ Nevertheless, he went on, ‘‘Given this perfect storm of human error, mistakes and miscommunication by all involved that day, the evidence did not indicate criminal conduct by police.’’

‘‘Perfect storm of human error’’ was a revealing choice of phrase to describe what happened in Cleveland. McGinty evoked a remarkable convergence of factors to describe a death that was, in fact, a direct result of two simple errors made in sequence in a matter of minutes. On the afternoon of Nov. 22, 2014, a man waiting for the bus near the Cudell Recreation Center, on Cleveland’s west side, called 911 and reported: ‘‘There’s a guy with a pistol. It’s probably fake, but he’s like pointing it at everybody.’’ The man added that the person with the gun was ‘‘probably a juvenile.’’ A police dispatcher swiftly notified patrol cars of ‘‘a guy sitting on the swings pointing a gun at people,’’ without the caveat that it might not be real. As the officers Frank Garmback and Timothy Loehmann pulled up at the scene, Rice approached their car with his hands out of his pockets, then dropped them to his waist. Loehmann fired almost immediately. It was only later that a detective noticed a green plastic B.B. next to the gun’s magazine and realized that the weapon was a replica.

An incompletely related report and an inaccurate assessment of a threat: Neither was unavoidable, and the way in which one led to the next was not complicated. But calling the incident a ‘‘perfect storm’’ implicitly presented the people involved not as individuals with agency but as unwitting executors of a systemic failing beyond anyone’s control. It expressed a measure of regret while lifting the incident out of the range of arguments about race and police violence. In the terms of Old Testament prophets and insurance underwriters, it recast an act of man as an act of God.

When did ‘‘perfect storm’’ become a metaphorical absolution? The phrase, in the sense that McGinty meant it, has its origins on a cold, clear morning in the winter of 1993, when an aspiring writer named Sebastian Junger drove from Cape Cod to meet a meteorologist named Bob Case at the National Weather Service’s office in Taunton, Mass. Junger was writing about the sinking of the Andrea Gail, a swordfish boat that went down in the North Atlantic with all hands in an October 1991 storm. The storm was a ferocious anomaly, a product of a three-way collision between a storm system moving eastward from the Great Lakes, a hurricane sweeping up the coast and a cold front from Canada. Case sat for hours trying to explain it to Junger, but ‘‘I struggled to understand what he was talking about,’’ Junger recalls. ‘‘He finally, in frustration, said, ‘Look, it was the perfect storm!’ ’’