Boylston Street's 26-mile marker will be a welcome sight to the thousands of runners who are in today's Boston Marathon. Today marks the 118th running of the race. Jared Wickerham/Getty Images hide caption

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Blue and yellow are the colors for tributes to victims of the Boston Marathon. Street lights on the route of this year's race are among the places they're showing up. Andrew Burton/Getty Images hide caption

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Carol Downing is still haunted by memories of last year's marathon. But she's excited about reuniting with other survivors. Michael Dwyer/AP hide caption

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Boston bombings suspect Dzhokhar Tsarnaev on April 19 as he emerged from a boat stored in a Watertown, Mass., backyard. The red dot of a police sharpshooter's laser sight can be seen on his forehead. Mass. State Police Sgt. Sean Murphy/Boston Magazine hide caption

itoggle caption Mass. State Police Sgt. Sean Murphy/Boston Magazine

Boston bombings suspect Dzhokhar Tsarnaev on April 19 as he emerged from a boat stored in a Watertown, Mass., backyard. The red dot of a police sharpshooter's laser sight can be seen on his forehead. Mass. State Police Sgt. Sean Murphy/Boston Magazine hide caption

itoggle caption Mass. State Police Sgt. Sean Murphy/Boston Magazine

Boston bombings suspect Dzhokhar Tsarnaev emerges from a boat stored in a Watertown, Mass., backyard on April 19. The red dot of a police sharpshooter's laser sight can be seen on his forehead. This is among the images that Massachusetts State Police Sgt. Sean Murphy gave to Boston Magazine. Mass. State Police Sgt. Sean Murphy/Boston Magazine hide caption

itoggle caption Mass. State Police Sgt. Sean Murphy/Boston Magazine

Boston bombings suspect Dzhokhar Tsarnaev on April 19 as he emerged from a boat stored in a Watertown, Mass., backyard. The red dot of a police sharpshooter's laser sight can be seen on his forehead. Mass. State Police Sgt. Sean Murphy/Boston Magazine hide caption

itoggle caption Mass. State Police Sgt. Sean Murphy/Boston Magazine

April 20 in Watertown, Mass.: Investigators work in and around the boat in which Boston bombings suspect Dzhokhar Tsarnaev was found hiding. Darren McCollester/Getty Images hide caption

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