As Boston reeled, younger bombing suspect partied

As the world hunted him, the younger brother suspected in the Boston Marathon bombings acted like any other college sophomore.

Dzhokhar Tsarnaev, 19, was on the campus of University of Massachusetts-Dartmouth every day after the attack until late Thursday, a university official told CNN. Tsarnaev attended classes and dorm parties and went to the gym while the rest of Boston came to a tense standstill.

A student at the school told The Boston Globe that she saw Tsarnaev at a party Wednesday night that was attended by some of his friends from intramural soccer.

"He was just relaxed," she said, asking the paper not to print her name.

Another UMass Dartmouth student said he talked about the bombing with Tsarnaev for several minutes Tuesday while they were working out at the gym. Tsarnaev seemed normal, perhaps a little tired, Zach Bettencourt told CNN.

Bettencourt said he told Tsarnaev something about the bombing, to the effect of, "You hear about this kind of thing happening in Iraq and Afghanistan, but not here."

"He was like, 'Yeah, tragedies happen like this all the time and it's sad,' " Bettencourt said, adding he had no inkling about anything suspicious with Tsarnaev, whom he described as a nice guy.

The days-long drama that gripped Boston -- and the world -- began when two homemade bombs made from pressure cookers exploded 12 seconds apart near the finish line of Monday's Boston Marathon. Three people were killed, and more than 170 wounded as nails, ball bearings, BBs and shards of broken glass were blasted through the viewing area.

Law enforcement officials combed through photos and surveillance videos, searching for clues to who detonated the bombs. The FBI released photos showing two men they were seeking and asked for the public's help.

At the dorm where Tsarnaev lived, students joked Thursday as they viewed the FBI photos on television, a senior who lived in the suspect's dorm told The Boston Globe.

"We made a joke like, that could be Dzhokhar," said Pamala Rolon. "But then we thought it just couldn't be him. Dzhokhar? Never."

A tense scene began to unfold Thursday night -- complete with wailing sirens, flashes of blue and red lights, a hail of bullets and explosions from homemade bombs. By early Friday morning, Tsarnaev's older brother, Tamerlan, 26, was dead. Dzhokhar Tsarnaev was bleeding as he stole away into the night.

On campus nobody was joking. The school posted a message on its website: "UMass Dartmouth has learned that a person being sought in connection with the Boston Marathon bombing has been identified as a student registered at UMass Dartmouth. The campus is closed. Individuals on campus should shelter in place unless instructed otherwise."

The manhunt for Dzhokhar Tsarnaev lasted all day Friday and left Boston streets deserted as police asked everyone to stay indoors. Then after the request was lifted, authorities got a tip: A Watertown man told police someone was hiding in his boat in the backyard, bleeding. It was their suspect, Watertown police Chief Edward Deveau said.

Officers spotted Tsarnaev poking through the tarp covering the boat, and a shootout erupted, Deveau said. Police used "flash-bangs," devices meant to stun people with a loud noise, and negotiated with Tsarnaev for about half an hour.

"We used a robot to pull the tarp off the boat," David Procopio of the Massachusetts State Police said. "We were also watching him with a thermal imaging camera in our helicopter. He was weakened by blood loss -- injured last night, most likely."

A thermal image photograph, released Saturday by the state police, showed what authorities say was Tsarnaev lying in the middle of the boat.

Police had no idea whether he had weapons or explosives with him, so they repeatedly told him to stand up and lift his shirt to show he wasn't wearing a device, Deveau said.

Eventually Tsarnaev stood up and lifted his shirt for the officers.

"Once we saw that, we felt comfortable enough to send some officer tactical equipment to grab him and pull him away from the boat," Deveau said. He was taken by ambulance to a hospital.

Police are confident there are no other suspects, Deveau said.

"These two acted together and alone," he said. "As far as this little cell and this little group, I think we got our guys."