Boston Marathon bombing timeline
Bombs at finish line killed 3, injured more than 260 on April 15, 2013
A timeline follows of events related to the Boston Marathon bombing, which killed three people and injured more than 260 others on April 15, 2013. On May 15, 2015,, a federal jury sentenced convicted bomber Dzhokhar Tsarnaev to die by lethal injection.
Russian FSB intelligence security service gives FBI information that Tamerlan Tsarnaev, of Cambridge, Mass., is a follower of radical Islam.
FBI closes investigation after finding nothing to link Tamerlan Tsarnaev to terrorism.
Sept. 12, 2011
Bodies of three men are found in Waltham, Mass., with their throats slit and marijuana sprinkled over them.
U.S. officials add the Tsarnaevs' mother to a federal terrorism database after Russia contacts CIA with concerns they were religious militants about to travel to Russia. She later says she has no links to terrorism.
Tamerlan arrives in Russia, where he spends time in two predominantly Muslim provinces, Dagestan and Chechnya.
Officials in Dagestan say Tamerlan applies for a new passport but never picks it up. Russian officials say they have him under surveillance but lose track of him after the death of a Canadian man who had joined an Islamic insurgency in the region.
July 17, 2012
Tamerlan returns to U.S.
Islamic Society of Boston Cultural Center in Cambridge says Tamerlan has an outburst that interrupts a sermon about it being acceptable for Muslims to celebrate American holidays.
Islamic Society says Tamerlan has a second outburst after a sermon that includes praise for the Rev. Martin Luther King Jr.
April 15, 2013
Bombs go off at the finish line of the Boston Marathon, killing three people and injuring more than 260 others.
April 16, 2013
Federal agents say the bombs were made from pressure cookers packed with explosives, nails and other shrapnel, but they still don't know who detonated them or why.
April 17, 2013
U.S. President Barack Obama signs emergency declaration for Massachusetts and orders federal aid to supplement local response.
April 18, 2013
Investigators release photos and video of two suspects and ask for public's help identifying them. Later that night, Massachusetts Institute of Technology police officer Sean Collier is shot to death in his cruiser, allegedly by Tamerlan and Dzhokhar Tsarnaev. Prosecutors say they steal an SUV at gunpoint from a Cambridge gas station. The driver is held for about a half hour, then released unharmed.
April 19, 2013
Tsarnaevs have an early morning gun battle with authorities who have tracked them to Watertown. Tamerlan, who is run over by his younger brother, dies. Dzhokhar escapes, and around 6 a.m., authorities tell residents of Boston and surrounding communities to stay indoors. All mass transit is shut down. That order is lifted around 6:30 p.m., just before authorities trace Dzhokhar to a Watertown backyard, where he is found hiding in a boat and taken into custody.
April 22, 2013
Dzhokhar Tsarnaev, injured in the shootout, is charged in his hospital room with using and conspiring to use a weapon of mass destruction.
April 30, 2013
Two friends of Dzhokhar's are charged with attempting to destroy evidence by disposing of a backpack and laptop computer taken from his room after they found he was a suspect in the bombing. Another is charged with lying to investigators.
May 9, 2013
Tamerlan Tsarnaev is secretly buried in Virginia after a weeklong search for a cemetery willing to take the body.
May 22, 2013
An FBI agent in Orlando, Fla., fatally shoots Ibragim Todashev, a friend of Tamerlan's, after he lunges at law enforcement officials questioning him about the Waltham killings. Officials say that before he died, he had agreed to give a statement about his involvement.
July 10, 2013
Dzhokhar Tsarnaev pleads not guilty to 30 federal charges.
July 23, 2013
Marc Fucarile is the last survivor of the bombings to leave the hospital.
Jan. 30, 2014
Prosecutors announce they will seek the death penalty against Dzhokhar.
April 15, 2014
Ceremonies and events mark the anniversary of the attacks.
April 21, 2014
The 2014 Boston Marathon features a field of 36,000 runners, 9,000 more than 2013 and the second-biggest field in history.
May 30, 2014
Khairullozhon Matanov, 23, is arrested on charges of obstructing the investigation by deleting information from his computer and lying to investigators.
June 18, 2014
Tsarnaev's lawyers file first of several requests to move the trial to Washington, D.C.
July 21, 2014
Azamat Tazhayakov, a college friend of Dzhokhar's, is convicted of obstruction of justice and conspiracy for agreeing with another friend to get rid of a backpack and disabled fireworks they took from his dorm room three days after the attack.
July 22, 2014
Stephen Silva, believed to have provided the gun used by the Tsarnaevs to kill Collier, is arrested on drug and weapons charges.
Aug. 22, 2014
Dias Kadyrbayev, 20, pleads guilty to impeding the investigation by removing incriminating evidence from Dzhokhar's dorm room.
Sept. 24, 2014
Judge grants delay and pushes start of trial to Jan. 5, 2015.
Oct. 28, 2014
Robel Phillipos, 21, is convicted of lying to federal agents about being in Dzhokhar's room.
Nov. 25, 2014
Federal judge rejects a request from lawyers for Tsarnaev to order prosecutors to turn over evidence about his older brother's possible participation in the Waltham slayings.
Dec. 18, 2014
Tsarnaev appears in court for first time since his July 2013 arraignment.
Jan. 5, 2015
Jury selection begins in Tsarnaev's trial.
March 4, 2015
Tsarnaev's lead defence attorney, Judy Clarke, declares in opening statements: "It was him."
April 6, 2015
Prosecutors and defence present closing statements.
April 7, 2015
Jury begins deliberating verdicts.
April 8, 2015
Jury convicts Tsarnaev; will weigh possible death sentence in forthcoming penalty phase of trial.
April 15, 2015
Second anniversary of Boston Marathon bombings.
April 20, 2015
119th running of the Boston Marathon.
April 21, 2015
Penalty phase of Tsarnaev's trial begins.
May 13, 2015
Prosecutors and defence make closing statements on sentence; jury begins deliberating.
May 15, 2015
Exactly 25 months after the attack, jury sentences Tsarnaev to death.