The defense sought to portray Tsarnaev as a member of a fractured family who easily fell under the spell of his 26-year-old brother, Tamerlan, who lawyers described as the mastermind of the April 15, 2013, attack that killed three people and injured 264.
It also echoed the recent words of the family members of some of the people killed by the 21-year-old ethnic Chechen in saying that sentencing Tsarnaev to prison for the rest of his life would both punish him and ensure he is removed from the intense media spotlight he has occupied for the past two years.
"No punishment could ever be equal to the terrible effects of these crimes on the innocent people who were killed and hurt or on their families," said defense attorney David Bruck. "There is no point in trying to hurt him as he hurt because it can't be done."
During the initial stage of Tsarnaev's trial, prosecutors portrayed him as an extremist who carried out one of the highest-profile attacks on U.S. soil since Sept. 11, 2001 because he wanted to "punish America" for military campaigns in Muslim-dominated countries.
Defense lawyers countered that Tsarnaev, whose family immigrated to the United States a decade before the attack, had been raised to idolize and obey his older brother.
"When people who knew Tamerlan heard that he bombed the marathon, it kind of fit. But people who knew Dzhokhar were stunned," Bruck said. "The man who conceived, planned and led this crime is beyond our power to punish. Only the 19-year-old younger brother who helped is left."
Tamerlan died following a gunfight with police early on April 19, 2013, hours after the brothers fatally shot a university police officer.
SLIM SUPPORT FOR CAPITAL PUNISHMENT
The death penalty remains highly controversial in Massachusetts, where state law does not allow the punishment to be applied, though Tsarnaev could face it because he is on trial in federal court.
A Boston Globe survey released on Monday found that just 19 percent of Massachusetts residents support the idea of putting Tsarnaev to death, fewer than the 30 percent who support the death penalty for "heinous" crimes. The poll of 804 people conducted April 22 and 23 has a margin of error of 3.5 percentage points.
In sharp contrast to the last phase of the trial, when the defense took just two days to call four witnesses, the court has scheduled about two weeks worth of testimony as Tsarnaev's lawyers make the case to spare his life.
Defense attorneys plan to call some members of his family, who traveled to Boston from Russia, a computer forensics specialist who will testify to Tamerlan's "obsessive" reading of jihadist literature, and an expert in brain development who will discuss the teenage mind.
It remains unclear whether Tsarnaev will speak in his own defense. He has been a quiet presence during the trial, offering no signs of emotion as the jury heard sometimes tearful testimony from survivors and viewed graphic, disturbing images of the bombs' detonation and aftermath.
Martin Richard, 8, Chinese exchange student Lu Lingzi, 23, and restaurant manager Krystle Campbell, 29, died in the bombing. The Tsarnaev brothers shot dead Massachusetts Institute of Technology police officer Sean Collier three days later.
Richard's parents and Collier's sister have spoken out publicly against federal prosecutors' pursuit of the death penalty, calling for a deal in which Tsarnaev would be sentenced to life in prison in exchange for giving up his right to appeal.
The first witness the defense called was the manager of a Halal meat market located about two blocks from the small Cambridge, Massachusetts, apartment where Tamerlan lived.
Tamerlan had twice been kicked out a nearby mosque when he interrupted the Imam's preaching to loudly disagree, testified Laith Albehacy.
Albehacy said the last time he saw Tamerlan was when he visited the market a few hours after the attack.
"I told him, 'Did you hear about the marathon bombing?' And he said, 'No,'" Albehacy said. "I told him a joke, 'You're not the one who did it?' And he smiled and said, 'No.'"