A congressional committee on Wednesday heard testimony from three witnesses about the events that led to deaths of four Americans at Benghazi in September, 2012. The Benghazi attack has become a political controversy — Republicans accuse the Obama administration of mishandling security there and of misleading the American public after the attack. One new allegation: that a four-person team set to deploy to Benghazi the night of the attack was told not to go.

Bill Gates is putting his money and time where his passion is: eradicating polio. The philanthropist talks with NPR's Robert Siegal about why it makes sense to spend an estimated $5.5 billion to wipe out the disease once and for all.