Two explosions near the finish line of the Boston Marathon on Monday killed three people and wounded scores. A look at the basics of the case:
Police arrested Dzhokhar Tsarnaev Friday night after finding him hiding in a boat parked behind a home in Watertown, the Boston suburb authorities shut down to conduct house-by-house searches. A flurry of gunfire broke out around the time officials lifted a shelter-in-place order that effectively shut down Boston and a number of surrounding suburbs. Tsarnaev, identified by authorities as Suspect No. 2, was on the loose for almost 20 hours after his brother, Tamerlan, was killed in a getaway attempt. Authorities said he was hospitalized in serious condition.
HOW THE SITUATION UNFOLDED
Surveillance tape late Thursday showed Suspect No. 2 at a gas station. The two suspects then shot a police officer responding to a report of a disturbance, authorities say. They carjacked a man, released him and got involved in a chase with police that resulted in explosives being thrown from the suspects' car and an exchange of gunfire, authorities say. Tamerlan Tsarnaev, identified as Suspect No. 1, died at a hospital.
Law enforcement officials and family members have identified the brothers as ethnic Chechen brothers who had lived in Dagestan in southern Russia. They had been in the U.S. for about a decade and lived near Boston, an uncle said. Dzhokhar Tsarnaev is a 19-year-old student at the University of Massachusetts at Dartmouth. Tamerlan was a 26-year-old boxer. Their motive remains unclear.
THE MARATHON EXPLOSIONS
Two bombs exploded about 10 seconds and 100 yards apart at about 2:50 p.m. Monday in Boston's Copley Square, near the finish line of the marathon. An 8-year-old boy, a 29-year-old woman and a 23-year-old graduate student from China were killed, and more than 180 people were wounded. The explosions occurred about four hours into the race and two hours after the winners had crossed the finish line, but thousands of runners were still on the course.
Authorities have said they believe the bombs used were fashioned out of ordinary kitchen pressure cookers packed with explosives, nails, ball bearings and metal shards. They suspect the bombs were hidden in duffel bags and left on the ground.