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, 47, has been charged with stealing food and other items from a camp in Rome, Maine. Knight's years of living in isolation earned him the nickname of the North Pond Hermit.
Credit Kennebec County Sheriff's Office / AP
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.
Boston firefighters talk with FBI agents and a crime scene photographer Tuesday at the scene of the Boston Marathon explosions.
Credit Charles Krupa / AP
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.