Boston Marathon terrorism attack In the tight rows of chairs stretched across the Commonwealth Ballroom, the nervousness - already dialled high by two bombs, three deaths and more than 72 hours without answers - ratcheted even higher. The minutes ticked by as investigators stepped out to delay the news conference once, then again. Finally, at 5.10pm Thursday, a pair of FBI agents carried two large easels to the front of the Boston hotel conference chamber and saddled them with display boards. They turned the boards backward so as not to divulge the results of their sleuthing until, it had been decided, they could not afford to wait any longer. I expected that I would feel relief, 'OK, now I can put a face to it,' and start some closure ... but I think I felt more doom. I felt, I don't know, chilled. Now the time had come to take that critical, but perilous step: introducing Boston to the two men believed responsible for an entire city's terror. Got him: a sign in a Boston hotel lobby shows a photo of Dzhokhar Tsarnaev the morning after he was captured. "Somebody out there knows these individuals as friends, neighbours, co-workers or family members of the suspects," said Richard DesLauriers, the FBI agent in charge in Boston. As he spoke, investigators flipped the boards around to reveal grainy surveillance-camera images of the men whose only identity was conferred by the black ball cap and sunglasses on one, the white ball cap worn backward on the other. Though it may be difficult, the nation is counting on those with information to come forward and provide it to us. Photographers and TV cameras pushed forward, intent on capturing the images, even as people in the lobby stared into computers and smart phones, straining to recognise the faces. Across the city, and across the country, so many people looked up and logged on to examine the faces of the men deemed responsible for the bombing attack of the Boston Marathon, that the FBI servers were instantly overwhelmed. Waiting game: a girl looks out her window as law enforcement searches for Dzhokar Tsarnaev. At the least, Bostonians told each other, the photos proved that the monsters the city had imagined were responsible for maiming more than 170 were nothing more than ordinary men. But even as that relief sank in, the dread that had gripped the city since Monday at 2.50pm. was renewed. If everyone had seen these photos, then that had to mean the suspects had seen them, too. What desperation might they resort to, marathoner Meredith Saillant asked herself, once they were confronted with the certainty that their hours of anonymity were running out? Chilling: A photograph, taken by a spectator 10 to 20 minutes before the Boston Marathon blasts, shows Dzhokhar and Tamerlan Tsarnaev in the crowd near the finish line. Photo: AP/Bob Leonard On the morning after the marathon, Saillant had fled the city for the mountains of Vermont with three friends and their children, trying to escape nightmares of the bombs that had detonated just below the room where they'd been celebrating her 3.38 finish. Now, she put aside her glass of wine, reaching for the smart phone her friend offered and scrutinised the photos of the men who had defeated her city on what was supposed to be its day of camaraderie and strength. "I expected that I would feel relief, 'OK, now I can put a face to it,' and start some closure," Saillant says. But I think I felt more doom. Knowing where we are and the era in which we live, I knew that as soon as those pictures went up that it was over, that something was going to happen ... like it was the beginning of the end. There was no way she or the people of Boston could know, though, just when that end would come - or how. Watching the action: neighbours use cameras to record images of the boat where Dzhokhar Tsarnaev was hiding. Perfect day takes a turn Marathon Monday dawned with the kind of April chill that makes spectators shiver and runners smile - the ideal temperature for keeping a body cool during 26.2 miles of pounding over hills and around curves. By the four-hour mark, more than two-thirds of the field's 23,000 runners had crossed the finish line, and the crowds of onlookers were beginning to thin a little. But the growing warmth made it an afternoon to relish. Passing the 25-mile mark, Diane Jones-Bolton, 51, of Nashville, Tennessee, picked up the pace, relishing the effort and the sense of accomplishment of her 195th marathon. Look for evidence: forensics officers search for clues. Near the finish line, Brighid Wall of Duxbury, Massachusetts, stood to watch the race with her husband and children, cheering on the competitors labouring through the race's final demanding steps. And at the corner of Newberry Street and Gloucester, cab driver Lahcene Belhoucet pulled over, relishing the overabundance of paying passengers on an afternoon that traditionally gives almost as much of a boost to Boston's economy as it does to the city's spirits. But the blast - so loud it recalled the cannon fire heard on summer nights when the Boston Pops plays the 1812 Overture - brought the celebration crashing down. Victims: photos of the deceased are displayed during Mass at the Cathedral of the Holy Cross on the first Sunday after the Boston Marathon bombings. "Everyone sort of froze, the runners froze, and then they kept going because you weren't sure what it was," Wall said. The first explosion was far enough away that we only saw smoke. Then the second bomb exploded, this time just 10 feet away. "My husband threw our kids to the ground and lay on top of them," Wall said. A man lay on top of us and said, 'Don't get up! Don't get up!'  Back in the field, Jones-Bolton noticed runners turning around and coming back at her. Then she realised most were wearing the blankets given to those who'd already completed the race. Suddenly the race came to halt, but nobody could say why. When word began to spread, Jones-Bolton panicked at the thought of her husband standing at the finish line, but was reassured by other runners. Culprits: Tamerlan Tsarnaev, 26, left, and Dzhokhar Tsarnaev, 19. At the finish, Wall, her husband and children raised their heads after a minute or two of silence. Beside them, a man was kneeling, looking dazed, blood dripping from his head. A body lay on the ground nearby, not moving at all. But in a landscape of blood and glass and twisted metal, they were far from alone. "We grabbed each other and we ran but we didn't know where to run to because windows were blown out so another man helped me pick up my daughter," and they ran into a coffee shop, out the back door into an alley and kept going. Meanwhile, the instincts of Dr Martin Levine, who has long volunteered to attend to elite runners at the finish line, told him to do just the opposite. Looking up at the plume of smoke, he estimated it was about two storefronts wide and quickly calculated how many spectators might be located in such an area. Fleeing the danger: an agent carries a child away from an area where one of the Boston bombing suspects was thought to be hiding. "Make room for casualties - about 40," he yelled into the runners' relief tent. Get the runners out if they can! And he took off. Just then the second bomb went off. He reached the site to find a landscape resembling a battlefield, littered with severed limbs. "The people were still smoking, their skin and their clothes were burning," he said. There were lower extremity body parts all over the place ... and all of the wounds were extreme gaping holes, with the flesh hanging from the bones - if there was any bone left. Back in his cab, Belhoucet said he mistook the first blast for an earthquake. Fearing that a building might collapse, he considered running. But then people came pouring down the street and he beckoned a family into the car. He grabbed the wheel, then turned momentarily to ask where they wanted to go. Crime scene investigators shake hands on Dartmouth Street at the corner of Boylston Street near the scene of the Boston Marathon bombings. Only then did he notice the man's face, dripping with blood. Faces in the crowd Now, three days after the bombing, investigators had made significant headway in deciphering the method behind the terror. Armies of white-suited agents had spent many hours sifting through the evidence littering Boylston Street, climbing to nearby rooftops to make sure no clue would go overlooked. But investigators still did not know why. And, more importantly, they had only the haziest idea of whom to hold responsible. It all came down to the photos, culled after a painstaking search of hundreds of hours of videotape and photographs gathered from surveillance cameras and spectators. But if they were unable to identify the men, that left the investigators with a difficult choice: They could keep them to law enforcement officers who so far had had no luck, prolonging the search and risking letting the men slip away or attack again. Or they could ask the public for help. But then, the suspects would know the net was closing in. When they decided to release them, it would only put Bostonians further on edge. "There was this kind of strange tension," said Brian Walker of Boston. You walk by people and you just kind of look at them out of the corner of your eye and check them out. I was conscious that I didn't feel comfortable walking around with a backpack. It was like I just want to be safe here and everybody is kind of jumpy. But as investigators pored over tips in the hours before the photos were made public, the city, at least, was struggling to right itself. On Monday, the bombs had exploded just a half-block before Brian Ladley crossed the marathon finish line. But, feeling lucky to be alive, he was out at 7am Thursday to join the line at the Cathedral of the Holy Cross, hoping to hear President Barack Obama speak at an interfaith service to honour the victims. The event was still hours away, but when tickets ran out, authorities spotted his marathon jacket and plucked him and some other runners out of line to watch the service in a nearby school auditorium. "If they sought to intimidate us, to terrorise us ... it should be pretty clear right now that they picked the wrong city to do it," Obama told the crowd of more than 2000 inside the church. We may be momentarily knocked off our feet. But we'll pick ourselves up. We'll keep going. We will finish the race. After it ended, Ladley found himself shaking hands with the President, too awestruck to remember their conversation. But what meant the most was the camaraderie of the crowd. "It was wonderful to have a moment with other runners and be able to share our stories," he said. The waiting game In the hours after investigators released the photos of the men known only as Suspect No. 1 and Suspect No. 2, the city went on about the business of a Thursday night, a semblance of normality restored except for the area immediately surrounding the blast site. Restaurants that had closed in the nights just after the bombing reopened for business. At Howl at the Moon, a bar on High Street downtown, the dueling pianists took the stage at 6 pm, almost as if nothing had changed. But across the Charles River in Cambridge, Tamerlan Tsarnaev, 26, and his brother Dzhokhar, 19, were arming up. Later, friends and relatives would recall both as seemingly incapable of terrorism. The brothers were part of an ethnic Chechen family that came to the US, in 2002. They settled in a working-class part of Cambridge, where the father, Anzor Tsarnaev, opened an auto shop. Tamerlan could be argumentative and sullen. "I don't have a single American friend," he said in an interview for a photo essay on boxing. He was clearly the dominant of the two brothers, a former accounting student with a wife and daughter, who explained his decision to drop out of school by telling a relative, "I'm in God's business." It's not that Tamerlan Tsarnaev didn't have options. For several years he'd impressed coaches and others as a particularly talented amateur boxer. He moved like a gazelle. He could punch like a mule," said Tom Lee, president of the South Boston Boxing Club, where Tsarnaev began training in 2010."I would describe him as a very ordinary person who didn't really stand out until you saw him fight." But away from the gym, Tamerlan swaggered around his parents' home like he owned it, those who knew him said. And he began declaring an allegiance to Islam, joined with increasingly inflammatory views. One of the brothers' neighbours, Albrecht Ammon, recalled an encounter in which the older brother argued with him about US foreign policy, the wars in Afghanistan and Iraq, and religion. The Bible, Tamerlan told him, was a "cheap copy" of the Quran, used to justify wars with other countries. "He had nothing against the American people," Ammon said. He had something against the American government. Dzhokhar, on the other hand, was "real cool," Ammon said. A chill guy. Since the bombing, the younger brother had maintained much of that sense of cool, returning to classes at the University of Massachusetts-Dartmouth and attending student parties. On the day of the bombing, he wrote on Twitter: "There are people that know the truth but stay silent & there are people that speak the truth but we don't hear them cuz they're the minority." But by Tuesday, when he stopped by a Cambridge auto garage, the mechanic, accustomed to long talks with Dzhokhar about cars and soccer, noticed the normally relaxed 19-year-old was biting his nails and trembling. The mechanic, Gilberto Junior, told Tsarnaev he hadn't had a chance to work on a car he'd dropped off for bumper work. I need the car right now," Junior says Dzhokhar Tsarnaev told him. Now, with the photos out, it was time to move. Already, one of Dzhokhar's college classmates had taken to studying the photo of Suspect No. 2 - nearly certain it was his friend, although others were skeptical. It wouldn't take long for others to notice. Suspects' final rampage The call to the police dispatcher came in at 10.20pm Thursday: shots fired on the Massachusetts Institute of Technology campus in Cambridge. Ten minutes later, when police arrived to investigate, they found one of their own, university officer Sean Collier, shot multiple times inside his cruiser. He had been monitoring traffic near a campus entrance, said Cambridge Police Commissioner Robert Haas. The baby-faced 26-year-old Collier, in just a year on patrol, had impressed both his supervisors and the students as particularly dedicated to his work. A few days earlier, he'd asked Chief John DiFava for approval to join the board at a homeless shelter, in a bid to steer people away from problems before they developed. Now he was being pronounced dead at the hospital. Witnesses reported seeing two men. Fifteen minutes later, another call came in of an armed carjacking by two men. That was on Brighton Avenue, Haas said. For the next half-hour, the carjacking victim was kept in his car, had his bank card used to pocket $800 from an ATM and was told by his captors that they'd just killed a police officer and were responsible for the bombing, Watertown Police Chief Edward Deveau said. Haas said the man escaped from the car when his captors went into a Cambridge gas station, and he called police. Investigators had their break. Although police had previously said the carjacking victim had left his cellphone in the Mercedes SUV, enabling police to track its location via GPS, Haas said Sunday the phone was found on Memorial Drive near the gas station. It was past 11pm now, and as the Mercedes sped west into Watertown, one of Deveau's officers spotted it and gave chase, realising too late he was alone against the brothers driving two separate cars. When both vehicles came to a halt, Deveau said, the men stepped out and opened fire. Three more officers arrived, then two who were off-duty, fending off a barrage. When a Massachusetts Bay Transportation Authority officer, Richard Donohue, pulled up behind them, a bullet to the groin severed an artery and he went down. "We're in a gunfight, a serious gunfight," Deveau said. Rounds are going and then all of the sudden they see something being thrown at them and there's a huge explosion. I'm told it's exactly the same type of explosive that we'd seen that happened at the Boston Marathon. The pressure cooker lid was found embedded in a car down the street. In the normally quiet streets of Watertown, residents rushed to their windows. "Now I know what it must be like to be in a war zone, like Iraq or Afghanistan," said Anna Lanzo, a 70-year-old retired medical secretary whose house was rocked by the explosion. As the firefight continued, Tamerlan Tsarnaev moved closer and closer to the officers, until less than 10 feet separated them, continuing to shoot even as he was hit by police gunfire, until finally he ran out of ammunition and officers tackled him, Deveau said. But as they struggled to cuff the older brother, he said Dzhokhar Tsarnaev jumped back in the second vehicle. All of the sudden somebody yelled 'Get out of the way!' and they (the officers) look up and here comes the black SUV that's been hijacked right at them. They dove out of the way at the last second and he ran over his brother, dragged him down the street and then fled," he said. Tamerlan Tsarnaev was rushed to a hospital, where he was pronounced dead. A few blocks over, Samantha England, was heading to bed when she heard what sounded like fireworks. When she called 911, the dispatcher told her to stay inside, lock the doors and get down on the floor. She reached for the TV, trying to figure out what was going on. "As soon as they said it on the news, that's when we started to freak out and realise they were here," England said. But after all the gunfire, the younger Tsarnaev had vanished. Officers, their guns drawn, moved through the neighbourhood of wood-frame homes and cordoned off the area as daylight approached. At Kayla DiPaolo's house on Oak Street, she scrambled to find shelter in the door frame of her bedroom as a bullet came through the side paneling on her front door. At 8.30 a.m., Jonathan Peck heard helicopters circling above his house on Cypress Street and looked outside to see about 50 armed men. "It seemed like Special Forces teams were searching every nook and cranny of my yard," he said. Unable to find Tsarnaev, authorities announced they were shutting down not just Watertown, but all of Boston and many of its suburbs, affecting more than 1 million people. But as the hours went by, and the house-to-house search continued, investigators found no sign of their quarry. Finally, at about 6.30pm, they announced the shutdown had been lifted. At the Islamic Society of Boston, Belhoucet, the cab driver who'd fled the bombing scene, arrived for evening prayer only to find it shuttered. But he told himself the city's paralysis could not continue much longer. "Because there is no place to hide," Belhoucet said. His picture is all over the world now. Across Watertown, people ventured out for the first time in hours to enjoy the day's unusually warm air. They included a man who took a few steps into his Franklin Street backyard, then noticed the tarp on his boat was askew. He lifted it, looked inside and saw a man covered in blood. He rushed back in to call police. And again, the neighbourhood was awash in officers in fatigues and armed with machine guns. The man hunkered down inside the boat, later identified as Dzhokhar Tsarnaev, traded fire with police for more than an hour, until at last, they were able to subdue him. Around 8.45 pm, police scanners crackled: "Suspect in custody." On the Twitter account of the Boston police department, the news was trumpeted to a city that had been holding its collective breath over five days of fear: "CAPTURED!!! With that, Boston poured into the streets. In Watertown, officers lowered their guns and grasped hands in congratulation. Bostonians applauded police officers and cheered as the ambulance carrying Tsarnaev passed. But on Boylston Street, where the bombing site remained cordoned off, there was silence even as the crowd swelled, and tears were shed. "I think it's a mixture of happiness and relief," said Matt Taylor, 39, of Boston, a nurse who drove to Boylston Street as soon as he heard of the arrest. Nearby, Aaron Wengertsman, 19, a Boston University student, who was on the marathon route a mile from the finish line when the bombs exploded, stood wrapped in an American flag. It's humbling to see all these people paying their respects. They included 25-year-old attorney Beth Lloyd-Jones, who was 25 blocks from the bombings and considers them deeply personal, a violation of her city. She is planning her wedding inside the Boston Public Library, adjacent to where the bombs exploded. "Now I feel a little safer," she said. But she couldn't help but think of the victims who suffered in the explosions that started it all: "That could have been any one of us."