CAMBRIDGE, Mass. — On the day after two bombs exploded near the finish line of the Boston Marathon, Dzhokhar Tsarnaev tapped out an early-afternoon text message to a classmate at the University of Massachusetts at Dartmouth. Want to hang out? he queried. Sure, his friend replied.
In Boston, the police and the F.B.I. were mounting investigations that would end three days later with Mr. Tsarnaev’s capture and his brother’s death. But on that Tuesday afternoon, he lounged in his friend’s apartment for a couple of hours, trying to best him in FIFA Soccer on a PlayStation. That night, he worked out at a campus gym.
On Thursday afternoon, he ate with friends at a dormitory grill. By early Friday, he was the target of the largest dragnet in Massachusetts history.
To even his closest friends, Mr. Tsarnaev was a smart, athletic 19-year-old with a barbed wit and a laid-back demeanor, fond of soccer and parties, all too fond of marijuana. They seldom, if ever, saw his second, almost watertight life: his disintegrating family, his overbearing brother, the gathering blackness in his most private moments.
There were glimpses. But Mr. Tsarnaev was a master of concealment. “I have had almost two weeks to think about it, and it still makes no more sense than the day I found out it was him,” Jason Rowe, Mr. Tsarnaev’s freshman roommate, said in an interview. “Nothing seemed out of the ordinary.”
Mr. Tsarnaev now lies in a prison medical facility, charged by federal authorities with using a weapon of mass destruction — the bombs, packed with explosives extracted from fireworks — that killed three people and wounded more than 260 others on April 15. In the face of compelling evidence, many friends still find it hard to believe that the teenager they knew — the “cool guy,” the “great student” with a “heart of gold,” the kid who “would not provoke violence” — could willfully commit such an atrocity.
But there were oblique signs that the gulf between the private and the public person was widening. Between raunchy jokes and posts about girls and cars on Twitter, Mr. Tsarnaev described terrifying nightmares about murder and destruction. In the last year, he alluded to disaffection with his American life and the American mind-set.
And as the date of the marathon drew close, he dropped cryptic hints of a plan of action, and the righteousness of an unspoken cause.
Dzhokhar Tsarnaev was born in July 1993 in the former Soviet republic of Kyrgyzstan, the youngest of four children in a family that roamed for decades across the Caucasus and Central Asia looking for a stable home.
He spoke only broken English in 2002 when his father, Anzor, an ethnic Chechen, brought him to Massachusetts from the mostly Muslim region of Dagestan in Russia, eventually winning asylum by claiming political persecution. But by the time he entered Cambridge Rindge and Latin School in 2007, he spoke with barely a trace of an accent, blending seamlessly into a student body that was a mélange of immigrants and American-born students of all colors.
By all accounts, he thrived there. Jahar, as his fellow students called him — the rough pronunciation of his Caucasian name, adopted as his nickname — became a star student, winning a $2,500 scholarship upon his graduation in 2011. He loved literature and world history, particularly studies of his former homelands.
In sophomore year, he joined the school’s wrestling team as a novice and quickly grew so strong and skillful, one teammate said, that he could take down even coaches. His teammates say they looked up to him as a teacher and motivator. “We’d be running stairs for hours,” said another, Zeaed Abu-Rubieh, now 21. “Every time I’d stop, when I was thinking about leaving, he’d push me forward, physically push me. And he was strong. He’d say: ‘Go on. Run. You can do it.’ He believed in people.”
His teammates eventually voted him captain. One of the coaches, Peter Payack, said he deserved it. Despite the draining four-hour daily practice and trips at sunrise to weekend meets, he said, Mr. Tsarnaev maintained his academic record and proved a model of good sportsmanship and steady temperament.
Reporting was contributed by Jennifer Preston, Serge F. Kovaleski and Emily Rueb from New York; Richard A. Oppel Jr. and Dina Kraft from Cambridge; Kitty Bennett from St. Petersburg, Fla.; and Leanne Poirier from North Dartmouth, Mass.