Boston ( 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 was n'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 . 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 .
Defense in trial of Dzhokhar Tsarnaev rested after a month . Prosecution presented more than 90 witnesses over the course of less than three days .