To his father, he was a "true angel", and to a family friend "a beautiful boy in a tux" at a prom party. School friends found nothing remotely strange or off-putting about Dzhokhar Tsarnaev.
He was an all-star member of the wrestling team at the highly regarded Cambridge Rindge and Latin high school in Massachusetts, and winner of a $2,500 (€1,900) scholarship in 2011, his final year.
He left to take up a place at the University of Massachusetts in Dartmouth where, as far as his father, Anzor, was concerned, he was a dedicated second-year medical student.
"My son is a true angel," said Mr Tsarnaev, speaking from Makhachkala, in the Russian province of Dagestan. "He is such an intelligent boy. We expected him to come on holidays here."
According to reports, Dzhokhar became a US citizen last year – on September 11.
Friends expressed disbelief at how the sociable, if reserved, 19-year-old became America's most wanted man, suspected of bringing carnage to the Boston Marathon.
The only sign of trouble came when he was sacked as a lifeguard at Harvard University swimming pool last summer after turning up late once too often.
Larry Aaronson, a retired teacher at the Rindge and Latin school, wrote on a social networking site: "He could not have been a sweeter more gracious young man. I cannot believe he was capable of such a heinous crime and of so many murders."
Robin Young, a local radio DJ, tweeted: "He came to the prom party we had. Beautiful boy. Remember djoharn [sic] well, beautiful boy in tux at prom party and elsewhere."
Dzhokhar was clearly attached to his parents' homeland, Chechnya, which he had never visited, and to its faith, Islam. On his account with the Russian social networking site, VKontakte (In Contact) he says he speaks English, Russian and Chechen but was born in Dagestan, which borders Chechnya.
He added links to pages calling for independence for Chechnya, which lost its bid for secession from Russia after two bloody wars in the '90s.
The page reveals a sense of humour. The most recent post, from March 19, was a video featuring a man mimicking several accents from the Caucasus region. Beneath the video it says: "Islam is not a religion of terror! Judge Muslims on Islam, and not vice versa!"
Rebecca, a high school friend, said: "I think he seemed to keep to himself in that he was kind of reserved, but his demeanour was always friendly and he would show up at the big social gatherings. He was a familiar part of the community, he didn't isolate himself."
A high school friend, who asked to remain anonymous, added: "As recently as November I played pick-up basketball with him.
"I don't know what changed since then but evidently it was something pretty big." (© Daily Telegraph, London)