The group has been linked to killings and attacks on secular academics and atheist bloggers in Bangladesh. The wife was questioned in Bangladesh and told investigators that her husband discussed Rahman's writings with her during his last visit home, Islam said. Ullah is accused of strapping a crude pipe bomb to his body and detonating it during rush hour Monday. Relatives and police said Ullah last visited his wife and newborn son in Bangladesh in September, after which he returned to the United States. Muslim-majority Bangladesh is governed by largely secular laws but the impoverished nation has struggled with a rise in radical Islam in recent years.