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UNKNOWN - APRIL 19: In this image released by the Federal Bureau of Investigation (FBI) on April 19, 2013, Dzhokhar Tsarnaev, 19-years-old, a suspect in the Boston Marathon bombing is seen. After a car chase and shoot out with police one suspect in the Boston Marathon bombing, Tamerlan Tsarnaev, 26, was shot and killed by police early morning April 19, and a manhunt is underway for his brother and second suspect, 19-year-old suspect Dzhokhar A. Tsarnaev. The two are suspects in the bombings at the Boston Marathon on April 15, that killed three people and wounded at least 170. (Photo provided by FBI via Getty Images)
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Story highlights

Defense in trial of Dzhokhar Tsarnaev rested after less than three days

Prosecution presented more than 90 witnesses over the course of a month

(CNN) —  

The defense in the trial of Boston Marathon bomber Dzhokhar Tsarnaev rested Tuesday afternoon after presenting only four witnesses.

Closing arguments are scheduled for Monday.

The defense case lasted less than two days, while the prosecution presented more than 90 witnesses over the course of a month.

Federal prosecutors rested their case Monday with grisly testimony about how the bomb Dzhokhar Tsarnaev placed near the marathon’s finish line tore through the bodies of 8-year-old Martin Richard and Lingzi Lu, a 23-year-old grad student.

A second bomb placed by Tsarnaev’s brother, Tamerlan, killed Krystle Campbell, a 29-year-old restaurant manager.

The short presentation in the sensational trial wasn’t surprising, given that Dzhokhar Tsarnaev’s attorney, Judy Clarke, acknowledged during opening statements that “it was him,” referring to her client’s culpability.

Testimony ended with an FBI fingerprint investigator who talked about numerous pieces of evidence with Tamerlan’s fingerprints and not Dzhokhar’s.

Earlier, a computer expert testified about computer searches on Tamerlan’s computer – including gun stores, transmitters, fireworks firing system, detonator and Boston Marathon – in the weeks before the bombing. Similar searches were not found on Dzhokhar’s computer.

Jurors first will be asked to determine whether Tsarnaev is guilty of 30 counts. Because 17 of those counts carry the death penalty as a possible punishment, a second phase of the trial will follow if the jury convicts him.

In the penalty phase, jurors will be asked to weigh aggravating factors, such as the heinousness of the crime, versus mitigating factors, such as Tsarnaev’s family history and his youth. He was 19 at the time of the bombings.

Defense strategy focuses on sibling’s influence

The defense, which began calling witnesses Monday afternoon, has argued that Tsarnaev, known to friends as Jahar, fell under the sway of his more extremist older brother after their parents moved back to Russia. Jahar Tsarnaev was flunking out of the University of Massachusetts and had lost his financial aid at the time of the bombings.

Prosecutors William Weinreb, Aloke Chakravarty, Nadine Pellegrini and Steve Mellin presented witnesses who told the story of Tsarnaev’s alleged scheme with Tamerlan to build and detonate pressure cooker bombs as an act of jihad. The brothers, Muslims of Chechen descent, allegedly sought to kill Americans at an iconic public event to retaliate against U.S. policies they believed harmed and oppressed Muslims abroad.

Prosecutors delved into Tsarnaev’s text messages and Twitter posts and showed jurors militant material found in his laptop, phone and iPod. They included writings available online from top leaders of al Qaeda.

They used data mined from a GPS device and store receipts to trace the purchase of the pressure cookers, BBs and ammunition. Jurors saw photos of pressure cooker parts, fuses, Christmas lights and other bombmaking materials found in the Tsarnaev family’s Cambridge apartment, where Tamerlan lived with his wife and child.

And they showed security surveillance videos of the brothers in the crowd near the finish line: In one, Dzhokhar Tsarnaev can be seen blending in with the crowd behind the Richard family for four minutes. He appears to slide a backpack off his shoulder near a tree and walk off, glancing over his shoulder. He broke into a run as the bomb went off.

After the surveillance photos were released to the public three days after the bombing, the brothers allegedly embarked on a desperate – and deadly – attempt to escape.

Jurors heard from carjacking victim Dun Meng and saw the brothers on convenience store surveillance video shortly before Meng’s escape. He can be seen jumping out of his leased Mercedes SUV at a gas pump and running across the screen as Dzhokhar Tsarnaev casually strolls through the store, picking up an armload of snacks.

Prosecutors also used ballistic evidence to link the brothers to the shooting of a campus cop at the Massachusetts Institute of Technology and a gunbattle with police in Watertown.

Tamerlan Tsarnaev, 26, died as a result of that gunbattle. The defendant, allegedly attempting to run down police, instead ran over his brother in the stolen Mercedes.

Jurors also viewed a boat in which Dzhokhar Tsarnaev sought refuge during the ensuing manhunt, which put Boston under a “shelter in place” lockdown.

He used a pencil to scrawl what prosecutors called his “manifesto” on the sides of the boat. It was pocked with bullet holes and streaked with blood.

He wrote he was jealous that his brother had achieved paradise by dying like a holy warrior in the gunbattle with police. He asked God to make him a martyr, too.

Tsarnaev has pleaded not guilty, although his attorneys do not dispute that he participated in the bombings. Clarke asked jurors in her opening statement to keep their minds open to an alternative explanation.

The defense began its case with two witnesses called to offer scenarios that differ from the version of events offered by FBI witnesses. One focused on the the defendant’s Twitter posts a year before the marathon, including mundane matters such as whether he should sleep in or get breakfast.

Another challenged the way the FBI used GPS points and store receipts to document the purchase of pressure cookers, BBs and ammunition – allegedly by Tamerlan Tsarnaev.

CNN’s Aaron Cooper contributed to this story.