Al Qaeda leader warns of 'gravest consequences' if Boston bomber executed

Al Qaeda leader Ayman al-Zawahri has warned the United States of the "gravest consequences" if Boston marathon bomber Dzhokhar Tsarnaev or any other Muslim prisoner is executed. Tsarnaev, named in a new online video message from Zawahri, was sentenced last year to death by lethal injection for the 2013 bomb attack, which killed three people and injured more than 260. “If the U.S. administration kills our brother the hero Dzhokhar Tsarnaev or any Muslim, it ... will bring America’s nationals the gravest consequences,” Zawahri said.