Boston Marathon Bomber Trial Update: Jury Begins Deliberations in Death Penalty Case

After hearing nearly 100 witnesses give gut-wrenching testimonies, the jury in the Boston Marathon bombing trial began its first day of deliberations on Tuesday.

The jury in the high profile case is tasked with deciding the fate of Dzhokhar Tsarnaev for his role in the Boston Marathon attack, which killed three people and injured 264 others on April 15, 2013. The 21-year-old suspected terrorist is facing 30 federal charges and the death penalty.

During the trial, Tsarnaev's lawyers argued that the accused bomber was under the influence of his older brother, Tamerlan, 26, in effort to save him from being put to death. Now the seven women and five men who sat on the jury panel will issue a likely guilty verdict before deciding the punishment he should face, reports ABC News.

On Tuesday, Judge George O'Toole immediately sent the jurors to begin weighing 30 criminal counts, which includes using weapons of mass destruction in public event as an act of terrorism, reports CNN. Seventeen of the counts being charged against him carry a sentence of death or life behind bars.

If Tsarnaev is found guilty of at least one of those 17 capital counts, then the trial will move into a penalty phase, where the same jurors will hear evidence of aggravating and mitigating factors to determine his punishment.

On Monday, the defense reiterated its argument that the suspect's older and now deceased brother was the mastermind behind the attacks.

"There is no excuse. No one is trying to make one. Planting bombs at the Boston Marathon was a senseless act," said defense attorney Judy Clarke, reports ABC News. "We are not asking you to excuse the conduct, but let's look at the varying roles. If not for Tamerlan, [the bombing] wouldn't have happened."

Prosecutors, on the other hand, argued that Clarke was trying to let her client "dodge full responsibility."

"He wanted to punish America. So that's what he did. He planted one bomb, his brother planted the other. It was a coordinated attack to maximize the terror," said Assistant U.S. Attorney Aloke Chakravarty, according to USA Today.