TOPSHOT - A picture shows an arm and a shoe in a mass grave in Bucha, on April 7, 2022, amid Russia's military invasion launched on Ukraine. - The UN humanitarian chief said on April 7 during a visit to the town of Bucha outside the Ukrainian capital Kyiv, which included a stop at the site of a mass grave that Ukrainians had dug near a church, that investigators would probe civilian deaths uncovered after Russian troops withdrew. (Photo by RONALDO SCHEMIDT / AFP)