Today, we are enlisting the public's help to identify the two suspects.
As we reported on Friday, that request for help from the public came on Thursday evening.
When the FBI released photos of two suspects in the Boston Marathon terror bombing.
Hours later, an officer at the Massachusetts Institute of Technology, 26-year old Sean Collier was killed, police say, by the same suspects.
Then there was a carjacking, and the chase in the middle of the night into the Boston suburb of Watertown, a shootout with police.
Sources told CNN the suspects threw a grenade and pipe bombs at officers.
We've heard gunshots, and then we saw the explosion .
Gunshots. And then like boom, boom—like the three big bangs.
Officers shot suspect number one.
26-year old Tamerlan Tsarnaev, who had explosives strapped to his body.
He died later.
His younger brother, 19-year old Dzhokhar Tsarnaev got away.
What we are looking for right now, is a suspect consistent with the description of suspect number two.
More than 9,000 officers were involved in the manhunt , much of Boston was under a lockdown, while authorities searched for suspect number two.
We believe this to be a terrorist , we believe this to be a man who's coming here to kill people.
By late Friday, there still hadn't been an arrest.
We do not have an apprehension of our suspect this afternoon, but we will have one.
Just one hour after that, officers had suspect number two cornered.
A citizen in Watertown told police someone was hiding in his boat.
It turned out to be suspect number two, Dzokhar Tsarnaev.
They are yelling loudly, to someone that are in the boat or near out, come out, and we just heard him say come out on your own terms, we also heard them say come out with your hands up.
And then at 8:45 ..
The Boston Police Department has just tweeted "Suspect in custody."
Celebration on the streets of Boston.
We've closed an important chapter in this tragedy.
Despite the celebrations, there is still tragedy.
Four lives are lost, Krystle Campbell, Martin Richard Lingzi Lu and Sean Collier.
Many others are seriously injured. Technology played a crucial from the moment of the investigation began on Monday.
And it was part of the capture on Friday evening as well.
Tom Foreman explains the details.
to recognize someone or something and say or prove who or what they are
The test can identify the presence of abnormalities in the unborn child.
the fact of something such as a bomb exploding
The atomic explosion is always accompanied by huge fireball.
a narrow piece of leather or other strong material used for fastening something or giving support
Her camera strap has broken.
an organized search for a person, especially a criminal
The police have launched a massive manhunt for the escapees.
someone who uses violent action, or threats of violent action, for political purposes
Without my gun, I'm a sitting duck for any terrorist.