Dawit was watching television at a relative’s one-room apartment in Axum, a historic city in Ethiopia’s war-torn, northern Tigray region, in early March when a news bulletin flashed up on the screen.

Graphic, unverified footage had surfaced of a mass killing near Dawit’s hometown of Mahibere Dego, in a mountainous area of central Tigray. In the shaky video Ethiopian soldiers appeared to round up a group of young, unarmed men on a wind-swept, dusty ledge before shooting them at point-blank range — picking them up by an arm or a leg and flinging or kicking their bodies off a rocky hillside like ragdolls.