How will jury decide whether Boston Marathon bomber gets death penalty?

Twelve jurors began the process Wednesday of weighing whether Dzhokhar Tsarnaev deserves to be sentenced to death for his role in the Boston Marathon bombings.

The day began with Judge George O’Toole walking the jury through the 24-page verdict form. Mr. Tsarnaev has been convicted on 30 charges relating to the April 2013 bombings that killed three people and injured more than 260. He also was found guilty of the murder of Sean Collier, a Massachusetts Institute of Technology security guard who was shot and killed three days after the bombings.

The form lists the charges against Tsarnaev, as well as the aggravating factors that justify a death sentence in the prosecution's view, and the mitigating factors that justify a sentence of life without parole in the defense's view.

Aggravating factors include the premeditated nature of the act; the fact that the offense was committed "in an especially heinous, cruel, and depraved manner" that involved serious physical abuse to the victim; and the young age of one of the four victims, Martin Richard.

Mitigating factors include Tsarnaev's age at the time of the bombings, 19; the fact that he had no prior history of violence; and that he was under the influence of his older brother, Tamerlan Tsarnaev, who died in a shootout with police several days after the bombings.

“You shouldn’t just do a mathematical count of each factor and decide with which is greater,” Judge O’Toole said. “You may find one mitigating factor outweighs all the aggravating factors combined. You may find a single aggravating factor sufficiently outweighs all the mitigating factors combined.”

Before the jury left the courtroom to begin deliberations, prosecutor Steve Mellin gave the government’s closing statement.

“Why does this murder deserve the death penalty while other murders do not?” Mr. Mellin asked. 

“The defendant didn’t simply kill people. He killed them using a weapon of mass destruction,” he said. “Its purpose is not to kill a specific victim, its purpose is to kill indiscriminately. And not just kill. Destroy.”

Mellin described the testimony on the four victims in the case: Krystle Campbell, Lingzi Lu, Martin, and Mr. Collier.

Ms. Campbell’s father, he said, told the jury in testimony how “she was the light of his life, how she would call him every day. Now that light is out and no phone call will ever come.”

Pictures of the victims were shown to the jury as Mellin spoke. One showed Collier at his graduation from the police academy. In testimony, Mellin quoted Collier’s father describing the graduation as “the happiest day of Sean’s life.” 

“He was murdered performing that job,” Mellin said. “Sean Collier was the moral compass in the family; now he is gone forever.”

Near the end of his hour-long statement, he concluded that not only do the aggravating factors of the case outweigh the mitigating factors, but that “frankly, it’s not even close.”

The aggravating factors, he said, “overwhelmingly tilt the scales of justice in only one direction.”

Mellin then reminded the jurors of their comments during jury selection almost five months ago.

“You all said that in the right case, if the government proved it was an extreme case, a heinous case, that you could vote to impose a sentence of death,” said Mellin. “This is that case.”

After a lunch break, defense attorney Judy Clarke made her closing statement, in which she told the jury they had already reached a decision on the Marathon bombing crimes by finding Tsarnaev guilty on all charges at the end of the trial’s first phase.

“You’re not just making a decision on the horrific nature of the crimes; you did that,” said Ms. Clarke. “You’re making a decision on who he is, who he was, and who he might become.”

Tamerlan Tsarnaev carried out the bombings with his brother, and the defense has focused its efforts to save their client from the death penalty by arguing that the older brother was the mastermind of the bombings. In her statement, Clarke fought against attempts by the government to minimize or disregard Tamerlan’s influence over his younger brother.

“Tamerlan did influence Dzhokhar. We need to talk about Tamerlan, someone needs to talk about Tamerlan,” said Clarke. “The story of Dzhokhar cannot be told without talking about Tamerlan, the Boston Marathon bombings cannot be understood in any degree of reality without talking about Tamerlan.”

“If not for Tamerlan this would never have happened,” she added. “The tragedy would never have occurred if not for Tamerlan.”

She concluded by quoting the government’s closing statement from the first phase of the trial, saying that the motivations for Tsarnaev’s actions were “an eye for an eye. You killed us, we’ll kill you." 

“If you believe that’s who Dzhokhar was, if you believe that’s who Dzhokhar is, that’s not who we are,” Clarke said.

“A sentence of life in prison without the possibility of release allows the possibility for hope,” she added. “Mercy is never earned, it is bestowed.”

The jurors will meet at court every weekday from 9 a.m. to 5 p.m. until they reach a decision. A death sentence would require all 12 jurors to agree that the case’s aggravating factors outweigh its mitigating factors. 

In this regard, their deliberations are notably different from the first phase. Instead of deciding collectively whether Tsarnaev is guilty of his crimes, they are being asked to decide individually what his sentence should be, O'Toole said. After spending months together listening to more than 150 witnesses over 27 days of testimony, the 12 Tsarnaev jurors must now ask themselves what sentence they think he deserves.

"This has been a long case and you have spent a long time together as jurors," O'Toole said. "Despite your regard for each other you should decide this case for yourself."