Bruins captain Zdeno Chara acknowledged a "Believe in Boston" sign at TD Garden. Jim Davis/Globe Staff
A US marshal walked outside during a bomb threat at the John Joseph Moakley United States Courthouse in Boston. Jessica Rinaldi/Reuters
At the marathon starting line in Hopkinton, a touching banner was hung in tribute to the bombing victims. Billy Baker/Globe Staff
An investigator carried an evidence bag off a roof top near the site of two explosions at the finish line of the Boston Marathon. Brian Snyder/Reuters
A crowd of journalists and people who were evacuated from the court stood in a parking lot during the bomb threat. Jessica Rinaldi/Reuters
Flowers and a Boston University key chain at a makeshift memorial for student 23-year-old Lu Lingzi from China. Stan Honda / AFP / Getty Images
Police and investigators worked for a third day on Boylston Street near the Boston Marathon finish line. AP Photo
A sign hangs on a barricade to Boylston Street at Berkeley Street. Bill Greene / Globe Staff
An investigator walked on a rooftop after reports that the lid of one of the pressure cookers was found on a rooftop. Reuters Photo
With the US Capitol in the background, American flags waved at half-staff at the Washington Monument. AP Photo
FBI crime scene investigators stood near an evidence marker on Boylston Street just past Berkeley Street. Darren McCollester / Getty Images
The remains of a black backpack that the FBI said contained one of the bombs that exploded during the Boston Marathon. FBI Photo
Martin Richard, 8, of Dorchester, was one of the victims of Monday's bombings. Courtesy of Richard family
