US Muslim leaders this week condemned the deadly bombing in Boston, as more details emerged about the suspects. Officials have described the Tsarnaev brothers as motivated by religious extremism but said they did not have ties to terrorist organizations. Some attention has focused on a Boston mosque where the suspected bombers occasionally prayed, after reports of heated exchanges between the older brother and an imam there. In a statement, the Islamic Society of Boston Cambridge denounced the suspects’ views as counter to its moderate American Islamic theology. The imam of a mosque in Washington, DC, said what happened in Boston was a criminal act, not a religious act. Other faith groups appealed for calm after last week’s attack. Boston Cardinal Sean O’Malley urged Catholics to be a people of reconciliation, not revenge, and representatives of the Sikh community expressed concern over possible retaliation against members of their faith who are sometimes mistaken for Muslims.