Now, the twin bombings at the Boston Marathon struck at a very special type of sporting event. Marathons have been called the most democratic of sports, with the fewest physical barriers between athlete and spectator.
NPR's Mike Pesca examines whether the attack could permanently damage that accessibility.
Christopher Knight, whose 27 years of living in near-total isolation in Maine's wilderness made him an object of fascination after he was arrested for stealing food and supplies, appeared by video for a court hearing Tuesday, when a Kennebec County judge set his bail at $25,000 cash.
As investigators combed through evidence in the deadly Boston Marathon bombings, seeking both motive and perpetrator, we turned Tuesday to a security expert for guidance on how the investigation may be unfolding.
Bryan Cunningham, a former CIA officer, assistant U.S. attorney and deputy legal adviser for the National Security Council, served in both the Clinton and George W. Bush administrations. He is now a senior adviser at the consulting firm the Chertoff Group, co-founded by former Homeland Security Director Michael Chertoff.