'5 Days': The Hunt for the Boston Marathon Bombers

While more than 30,000 runners trekked through Boston today, the moments of hope and victory seem so different than they did three years ago after the deadly finish line bombings tonight, we'll take you deeper into that investigation with a dramatic video and chilling new details on how that man

hunt

ended with a man's backyard mass shooting here's ABC's chief investigative correspondent Brian Ross great run y'all it was a happy day in Boston until that first explosion in 249 heads turned to the sound of the explosion 200 yards away oh my god let them fly something exploded oh my god something happened in the next 12 seconds some will decide to leave the restaurant area but most he will stay, including the Richard family, not realizing that the second bomb is planted in a backpack at his feet among the dead eight-year-old Martin Richard. hello properly gone what should have been joy turned into panic and heartbreaking fear of the worst i saw hungry people in the face i saw people crying i saw people leaving that seen a lot telepsychic seen in your face it was the beginning of five

days

of terror and tonight, three years later, the FBI in Boston, the police revealed that the firefighters were fired again and that for the next one hundred and two hours they would track down those responsible for an attack that marked the nation. responsible for this, it was a puzzle at the time and we had to piece it together bit by bit.

The most important piece of the puzzle would come from what is called the car lab at FBI headquarters in Boston, where agents collected surveillance video. along the race route this is the man they were looking for but for that first day they couldn't spot first slow down zoom in game again no luck he was hiding in plain sight we couldn't see anything stick out just after a bystander sent this photo on day two it all came together when the agents could see the backpack that contained the bomb right there that's the first time you've seen that's the first time so we saw that bag we said it was the bomb and then we started to look around that location around the bag who might have been responsible or who that bag belonged to the man in the white hat that was the aha moment so now the fbi team sent to track down the white hat attacker and we play the tape backwards to make sure we see where it's coming from going backwards picked up by the cameras at Walgreens and we can see it coming from here and on the ATM camera at Bank of America across from the Back Bay social club the next key piece The CCTV footage we receive is here at the whiskey restaurant.

Whitehead is seen with another man dressed in black, so when he saw them here, he knew he was the second person, absolutely that's where we now have the black hat and the white hat, but in the next two

days

. the case stalled. The agents had no idea whose black hat job and white hat job good afternoon money until the fourth, when the FBI made the fateful decision to release the surveillance photos publicly and the

bombers

rushed to strike again his radio call that there is an officer down and it turns out to be Officer Sean Collier at MIT the two are the naive brothers Tamerlan and Dzhokhar seen in this MIT surveillance video and they approached officer Colliers Park patrol car the killer is officer collier hoping to get his gun after failing to get his gun they run away steal a vehicle and drive into suburb watertown ok now vehicles move down here this hated thing in vehicle 89 covers around the Viggo being pinged Watertown police units moved towards Dexter I turn the corner and the bad guys raise their arms full the uptight reporter fired shots at the officers in front of the vehicle so I stood here I said okay , this is what I'm going to do, I jumped through it and I drove and I just jumped here and I was following it, it was like this they're moving God is moving and I'm following it like this and just shooting right in the middle of here using the door like kava I emptied my gun adam and meanwhile his gun ran out of ammunition the foiling through the gun hit me and my left bicep turned around he ran back to the street turned left I chased him and probably left About four or five feet in the air, I went down on the shoulders and brought him down, he had eight bullets in him and he was still fighting with us.

The only thing I had was my empty gun and I hit him with the pistol I was trying to knock him out I hit him as hard as I could ten twelve times I couldn't knock him out The younger tsarnaev now back in the stolen car hit him bro we just miss the officers , all the officers responded we have a body pinned down and we have another shot we also saw their taillights at that point with the youngest terrorist on the loose the whole city was locked down on the 5th and that applies here in Watertown where we are now and at this point everyone in

boston

we were all going house to house clearing them people hearing footsteps in their homes people running scared but after a long day the lockdown was canceled on

boston

police officers. they were about to return home until this man had his emergency 67 Franklin Watertown the home of David Henneberry, 66, the 9-1-1 call is heard here for the first time today I have a boat in my yard it's blood all inside this person on the boat i'm sure i just looked in the boat yes you can pour medicine but i can look at it right now it's ok i'm outside maybe i can tell i can hear don't put yourself in danger stay away from the bed i'm not going to go edek boat i'm absolutely not just down and we were literally the first on that boat man i went on the air and said we're here one more time clearly i'm still going to where the guy dies on the boat even though my wiring was that it seemed that he was poking around with a gun on his own. more than 250 shots into the boat itself and dozens more into surrounding houses this one missed a child's bed other rounds smashed into walls vases furniture in neighbors' houses you know we knew we had to stop that fire immediately and immediately immediate.

I'm yelling into my radio and I'm yelling: my guys in the yard don't shoot, don't shoot, only later did the police find out that the man on the boat did not have a gun who fired the first shot, I still don't know. I can honestly say none of our Boston guys got into a fight I had a good grip on my guys I had to watch Evans and his men finally surrounded the boat waiting for an FBI hostage rescue team to take over We threw smoke grenades at the boat and then eventually, then they negotiated, they were able to talk to him, just get him to sit in the boat ownership company and then they 100% detained him, that's ours, the young men are badly injured, but they survived while the medics treated him.

He asked what happened. to his brother but ever since he died from his injuries they told him you'll find out soon enough it was the best feeling I've ever had being Alethea and seeing people applauding the police do you know something I've never had seen? thanks to Brian Ross for that report, full episodes of five days of

hunt

ing down the Boston Marathon terrorists will be published daily on ABC News' digital platforms.