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The Maywand District killings, in which a group of army infantrymen murdered at least three Afghan civilians in early 2010, making their actions appear to be combat-related, seems almost too big to tackle. A dozen soldiers charged with crimes, 11 convicted, for a range of charges starting with premeditated murder and keeping human body parts as trophies down to drug use and obstruction of justice. Faced with that daunting subject, director Dan Krauss delivers a documentary in The Kill Team that narrows its focus down to a few soldiers and the conditions that allowed for them to commit these crimes.

As a full document of the incident, the film feels maddeningly incomplete. As a case study in our military’s moral failings, it’s grimly effective.

At the center of the doc is Spc. Adam Winfield, the first member of his platoon to attempt to report the murders; his reward for putting himself at risk of retribution from his fellow soldiers was a murder charge of his own. Neither Krauss nor Winfield’s family attempt to soft-pedal Winfield’s tacit complicity, but do paint him as a victim of both bureaucracy and an army that wasn’t interested in addressing his claims.

Krauss alternates between documenting Winfield’s defense, and presenting a chronology of the crimes, through the accounts of a handful of other soldiers convicted in the killings, along with the whistleblower who finally got the army’s attention. Their candor, in combination with the often gruesome photographs and videos they took in the field, make for a sobering wake-up call about how the U.S. is waging its wars. The bigger tragedy, and what makes the film important despite its limited perspective, is that while the military may claim these actions were anomalous, the picture painted by the documentary is one of institutionalized cruelty.

The film shows tonight at 5:30 p.m. at the National Portrait Gallery and Friday at 6:30 p.m. at AFI Silver Theatre.