Boston Bombing Day 5: Never-Before-Heard 911 Call That Ended It All

— -- [This is the final installment of an ABC News digital special report "5 Days," which tells the hour-by-hour, day-by-day story of the investigation into the 2013 Boston Marathon bombing, with behind-the-scenes details based on interviews and evidence gathered by the FBI and Boston law enforcement agents who worked the investigation. Click to see Day 1, Day 2, Day 3 and Day 4. "5 Days" is written by Brian Ross and reported by Brian Ross, Rhonda Schwartz, Michele McPhee, Megan Christie, Randy Kreider and Lee Ferran.]

David Henneberry, 66, was remarkably calm as he called 911 and told a Watertown police dispatcher the dramatic news: “I have a boat in my yard. There’s blood all over the inside. There’s a person in the boat.”

“Are you sure?” the operator asks.

“I just looked in the boat,” says the Watertown resident, with growing excitement.

Henneberry started the call while he was in his house but goes back outside to get a better look at the boat in his backyard. The emergency operator urgently orders him inside.

“Don’t put yourself in harm’s way. Stay away from the boat,” the operator says.

“I’m not going near the boat. I’m absolutely not going near the boat,” Henneberry says, his voice rising. “But it’s in my backyard. It’s pretty close. The person did not move when I opened up the [boat covering].”

On the 911 tape, obtained by ABC News, the operator immediately relays the startling news to officers in the field who had spent a fruitless day searching for the remaining Boston bomber, Dzhokhar Tsarnaev, the most wanted man in America. Dzhokhar’s older brother, Tamerlan Tsarnaev, had been killed in a violent firefight with police overnight.

It was the evening of Friday April 19, 2013, four days after two bombs ripped through crowds near the finish line of the Boston Marathon, killing three people including an 8-year-old boy and injuring more than 260 others.

Now every badge in the area was about to descend on the Watertown location.

An Anxious City on Lock Down

The people of Boston and its suburbs woke that Friday morning on edge. Officials had locked down the city because of what would later turn out to be two pieces of bad information: one from a cab driver who thought he dropped two terrorists off at a Boston train station, and a second in the form of a regular pipe found near the station was reported as a possible pipe bomb.

But one threat was very real: Dzhokhar Tsarnaev was still out there, hiding. Armed officers were going door-to-door in Watertown, the suburb where the firefight had taken place the night before.

“We were going house-after-house, clearing them,” then-Boston Police Superintendent William Evans said. “People were afraid in Watertown. They would see a backdoor open that they didn’t think was open before. We’d go into that house and clear it. People were hearing footsteps in their homes.”

At one point the FBI thought it had tracked the younger brother’s phone to a location near his college in Massachusetts.

“I was on the phone with FBI headquarters and Director [Robert] Mueller was on the line... And I said, ‘We don’t have the search warrant ready.’ And I remember him saying to me, ‘Well, if you’re ready, then you go on my word,’” recalled John Foley, then the No. 2 man in the FBI’s Boston office. “And I’m like, ‘Okay, roger that, sir.’

“I’m not sure if that’s ever happened before,” he said.

Foley said the FBI carried out the Mueller-authorized raid, but it too came up empty. Mueller, now working at a law firm in Washington, D.C., declined to comment for this report.

Elsewhere an elderly man left his home and was promptly surrounded.

“They had this robot go up and take some things off him,” Evans said. “There were a lot of false alarms. People are running scared.”

The FBI brought in dogs to help the search, but agents said they too came up with nothing. The authorities were getting somewhere when it came to the identities of the man they were chasing, however, thanks to the fingerprints of a dead man.

A Dead Bomber Still Has Uses

Overnight police had entered into a frenzied firefight with the two then-unidentified bombers, who were traveling together in a dark SUV. One of the bombers, Tamerlan, was shot several times by police, but wasn’t taken down until he was tackled by a police officer and then run over by Dzhokhar in the midst of his own getaway. The police officer who tackled Tamerlan managed to dodge the vehicle.

After the gunfight, Tamerlan was taken to a nearby hospital but was dead on the table. But who was he?

“We gotta roll the prints off the dead guy. Find Jeff," Foley recently recounted to ABC News.

Jeff was FBI agent Jeff Rollins, who was trained to use a portable quick capture fingerprint system that transmits prints to an FBI database in West Virginia.

“They [doctors] had finished working on him to try and resuscitate and obviously failed, so it was in a side room, with some of the medical equipment still attached,” Rollins said.

He rolled the device in, lifted Tamerlan's lifeless hand and took prints from his fingers and then rolled around the bed to take prints from the other hand. He submitted the prints and -- nothing. The connection had cut out, Rollins believed, due to the room’s thick walls.

“And right when someone opened the door - snap! The connection came back and there was an instantaneous hit,” Rollins said.

Tamerlan Tsarnaev. For the first time the FBI knew the identity of one of the bombers, and it wouldn’t take long for agents to discover that Tamerlan had a younger brother, Dzhokhar, who appeared to be the long-sought man in the white hat. The man still on the loose.

‘There’s a Body in the Boat’

At 6 p.m. that night, the Boston lockdown was lifted. Police in the area were preparing to head home. But then Henneberry made the fateful call about the figure in his boat.

“The boat’s in the backyard. There’s somebody laying on the floor in the backyard,” Henneberry says in the call. “I found something on the outside and I got nervous, and I looked in and I saw blood all over the floor of the boat and there’s a body in the boat... He didn’t move. He’s laying down alongside the engine, inside the boat.”

Less than two minutes later, sirens can be heard on the call as police in the area converge on the Franklin Street address.

Police Superintendent Evans said he and his men were the first on the scene, but soon the area was swarming with law enforcement officers from various agencies.

“I could see him [Dzhokhar] poking at the boat. I knew somebody was [onboard]. My worry was, it looked like he was poking with a gun,” Evans said.

At some point, someone fired a shot, which prompted other officials to let loose on the target. More than 250 bullets were shot into the boat itself and dozens more sliced through surrounding homes, including one that barely missed a child's bed.

“I knew we had to stop the firing right away. And I’m yelling on my radio and I’m yelling to my guys, and they’re yelling, ‘Hold your fire! Hold your fire!’” Evans said. “I didn’t want him killed because we didn’t know [how big of a terror] cell... and what information we had to gather. And, No. 2, I knew I had policemen all around that boat.”

Evans said that to this day, he doesn’t know who fired that first shot, but swears it wasn’t a Boston police officer. A review of the events by Harvard University would later report that it was “a tactical team member of an unspecified agency who had been stationed on a rooftop overlooking the boat.”

After the firing stopped, Evans said officers threw flash bang and smoke grenades into the boat. Then the FBI negotiated with the younger Tsarnaev, who was injured but miraculously still alive.

“They were able to talk to him, just get him to sit up on the boat and then he was taken into custody,” Evans said.

In a photograph obtained by Boston Magazine, what appears to be a sniper’s laser is shown trained on Dzhokhar’s head as he surrenders.

Investigators later discovered a bullet-riddled, blood-splattered message on one wall of the boat, apparently written by Dzhokhar: “The U.S. Government is killing our innocent civilians but most of you already know that. As a [Muslim] I can’t stand to see such evil go unpunished. We Muslims are one body. You hurt one of us, you hurt us all,” the message read in part. “Know you are fighting men who look into the barrel [of] your gun and see heaven.”

Evans said that when they got “100 percent” confirmation the man in custody was the guy they had been chasing, he could feel “the blood flowing out” of him.

It was over. Five days, five hours and 57 minutes after the first explosion changed Boston forever, the city was safe again.

Months later, Dzhokhar Tsarnaev would be convicted and sentenced to death, some measure of justice for the families of 8-year-old Martin Richard, 23-year-old Lingzi Lu and 29-year-old Krystle Campbell, who were killed in the marathon bombings, and 27-year-old Sean Collier, an MIT police officer who was assassinated during the brothers' violent rampage three days later.

The night that Dzhokhar Tsarnaev was finally put in handcuffs, Evans said he remembered leaving Watertown, exhausted.

“People [were] coming out of their houses, clapping, screaming,” he said. “It was the best feeling I’ve ever had... It’s almost like we won the war... It’s difficult in the job and it’s sometimes a thankless job, but to be out there and to actually see people clapping for police was something in my time in 32 years that I’ve never seen.”

Evans said he showed up for the press conference where the arrest was to be announced, but when he got there “everybody and their mother was on stage,” ready to take credit.

“I turned to my guys and said, ‘Hey, let’s get out of here. Let’s go get a beer.’”

Just catching up? Click to see Day 1, Day 2, Day 3 and Day 4 of this special report.

"Five Days": Research by Alex Hosenball, Cho Park, Zoe Lake and Michael Birnkrant. Video editing by Shilpi Gupta, Abhinav Bhat, and Karl Dawson. With ABC News Digital Senior Producer Eric Johnson, Managing Editor Xana O'Neil and Executive Producer Dan Silver.