7 Minutes: How Miriam Carey's U-turn at a White House checkpoint led to her death

"We want to know: Why? What happened?" So many questions, so much we still don't know about the case of the woman shot to death by the Secret Service and the U.S. Capitol Police on Oct. 3, 2013, after a car chase from the White House to Capitol Hill. Her 13-month-old daughter survived in a car seat.