A prominent rights group on Tuesday called for the International Criminal Court to investigate atrocities in Sudan’s volatile Darfur region, including what it says were “summary executions” of 28 non-Arab tribesmen by a Sudanese paramilitary force and allied Arab militias in May. Human Rights Watch said several thousand members of the paramilitary Rapid Support Forces and their allies rampaged through the Darfur town of Misterei, home to the non-Arab Massalit tribe, on May 28. The attack came as the paramilitary and Sudan’s army have been engaged in monthslong fighting that the United Nations says has brought Sudan to the brink of a full-scale civil war.