An Iranian parliamentary panel said Sunday that Tehran’s prosecutor, an ally of President Mahmoud Ahmadinejad, was responsible for the beating deaths of three imprisoned protesters last summer, state news agencies reported. The panel’s investigative report said the prosecutor, Saeed Mortazavi, who has since been promoted, was responsible for the violence against protesters in the notorious Kahrizak detention center, where at least three young men, including the son of a former Revolutionary Guards commander, were killed. The allegation was a rare criticism of a senior official involved in the government’s crackdown on the protest movement that erupted in June over disputed...