ONE YEAR LATER

April 17, 2013:

U.s. President Barack obama signs an emergency declaration for Massachusetts and orders federal aid to supplement the local response to the bombings.

April 18, 2013:

investigators release photographs and video of two suspects and ask for the public’s help in 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 s UV at gunpoint from a Cambridge gas station. the driver is held for about a half-hour, then released unharmed.

April 19, 2013:

the tsarnaevs have an early-morning gun battle with authorities who have tracked them to Watertown. tamerlan, who is also run over by his younger brother, dies. dzhokhar escapes, and at about 6 a.m., authorities tell residents of Boston and surrounding communities to stay indoors. All mass transit is shut down. that order is lifted at about 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, who was 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 tsarnaev 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 buried in an undisclosed location after a weeklong search for a cemetery willing to take the body.

May 22, 2013:

An F Bi agent in orlando, Fla., fatally shoots ibragim todashev, a friend of tamerlan tsarnaev, 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 tsarnaev.

April 15, 2014:

Ceremonies and events will mark the anniversary of the attacks.

April 21, 2014:

the 2014 Boston Marathon will feature a field of 36,000 runners, 9,000 more than 2013. it will be the secondbiggest field in the race’s history.