For bombing suspect’s nurses, angst gave way to duty They did what they had to do, and did it well. But they worry ← Related Article Visit The Boston Globe Share on Twitter Share on Facebook Comment on this Scroll to top of page David L. Ryan/Globe Staff Two bombs tore through the crowd around 2:50 p.m. on Boylston Street. John Tlumacki/Globe Staff Police officers with their guns drawn heard the second explosion down the street. John Tlumacki/Globe Staff Police looked at blown out windows at the scene of the first explosion. Jim Davis/Globe Staff Federal agents joined Boston police at the scene outside the emergency room of the Boston Medical Center. Aram Boghosian for The Boston Globe By early Tuesday, a memorial for the victims of the attacks began to form at Boylston and Berkeley streets. John Tlumacki/Globe Staff Investigators worked at the site of the second bomb explosion. Reuters Marathon bomb scene pictures taken by investigators showed the remains of an explosive device. Bill Greene/Globe Staff Officials spoke to the media Tuesday at their command post, the Westin Copley Place hotel. Ultimately, 1,000 investigators would be based there. Jim Davis/Globe Staff State Trooper Mike Currier and his dog "Chico" patrolled Terminal B at Logan Airport. Suzanne Kreiter/Globe Staff Armed members of the Regional Response Team took up position at City Hall. Barry Chin/Globe Staff A bomb threat on Wednesday caused the evacuation of the Moakley federal courthouse. Barry Chin/Globe Staff On Thursday, FBI agents released images of the suspects. They were later identified as Tamerlan and Dzhokhar Tsarnaev, brothers who emigrated with their family from Russia in 2002. Bob Leonard The bombing suspects together on the street, the day of the Boston Marathon attack. Aram Boghosian for The Boston Globe MIT Police Officer Sean Collier was shot to death late Thursday near the university in Cambridge. The alleged bombers were suspected. Essdras M Suarez/Globe Staff Law enforcement agencies congregated in Watertown following a police chase. Darren Mccollester/Getty Images Friday began with one suspect dead, a region locked down, and a massive manhunt underway. Barry Chin/Globe Staff SWAT teams conducted a house-to-house search in Watertown. Aram Boghosian for The Boston Globe State Police stopped a car at the intersection of Carver Road and Belmont Street in Watertown. Bureau of Alcohol, Tobacco, Firearms and Explosives A wounded Dzhokhar Tsarnaev was handcuffed, bringing the nightmare of a daylong manhunt to a dramatic end. Aram Boghosian for The Boston Globe After the arrest, police officers were cheered as heroes. One of them posed with admirers on Boston Common.