U.S. President Barack Obama was briefed for one hour Friday morning by top law-enforcement officials on the developments in the Boston Marathon bombing investigation, the White House said. The briefing in the White House Situation Room was led by Attorney General Eric Holder and Federal Bureau of Investigation (FBI) Director Robert Mueller. Vice President Joseph Biden attended the briefing, while Homeland Security Secretary Janet Napolitano, Central Intelligence Agency (CIA) Director John Brennan, and Secretary of State John Kerry participated via video conference.