Boston(CNN) Dzhokhar Tsarnaev's own words may determine whether he lives or dies, even if he never speaks a word at his trial.
The admitted Boston Marathon bomber has sat in silence as people who lost limbs sobbed or glared at him from the witness stand. He slouched in his chair as jurors watched videos of him both before and after two nail-packed pressure cooker bombs exploded, killing three people, claiming 17 limbs and hurting more than 260 others.
He didn't utter a peep as his tweets and words he had scribbled on the side of a pleasure boat flashed up on a big screen and were quoted in court.
At issue: Was Tsarnaev a terrorist looking to punish the United States for policies he believed were harmful to Muslims? Or, was he a goofball stoner who simply followed the lead of his older, more radical brother?
The defense team tried to portray Tsarnaev as a confused college kid who, like countless others, watches Comedy Central and cracks crass jokes. "I wanna study a broad or two," he posted on his Twitter account as @J_tsar. He jokes about not seeing commercials featuring the Trix rabbit, and about "whale watching" outside a McDonald's fast-food restaurant.
Miriam Conrad, a member of his defense team, tried Tuesday to apply a more benign spin on tweets the government contends show him as a would-be jihadist eager for martyrdom and a free pass to paradise.
His brother was dead and police knew who he was; they were scouring the Boston suburb of Watertown for Tsarnaev when he slipped under a tarp and climbed aboard the Slip Away II, a fishing boat dry-docked in a Watertown backyard. He hid for hours before being discovered.
Boston Marathon bombing evidence
A jury condemned Dzhokhar Tsarnaev to death on Friday, May 15, for his role in killing four people and wounding hundreds more in the 2013 Boston Marathon bombings. See photos that were released as evidence in his trial.
This undated photo of a young Tsarnaev with his brother, Tamerlan, was shown by the defense in the sentencing phase of the trial. Tamerlan died after being shot by police and run over by a car driven by his brother in the massive manhunt that followed the bombings.
Katie Russell met Tamerlan Tsarnaev at a nightclub and dropped out of college to marry him. Her mother, Judith Russell, testified that Tamerlan came between Katie and her family and that Katie became isolated. She eventually converted to Islam and changed her name to Karima Tsarnaeva. She was the breadwinner. But when company came for dinner, she cooked, served the men and then retired to another room.
This collection of photos of Dzhokhar Tsarnaev in his wrestling days was introduced by the defense.
This photo of Tamerlan Tsarnaev, recovered from his computer, was shown during the sentencing phase.
This image shows victims' positions in the crowd prior to the Boston Marathon bombings on April 15, 2013.
Tsarnaev "flips the bird" in a jail cell during his first arraignment on July 10, 2013. The image was presented to jurors in the sentencing phase of his trial.
Tsarnaev poses in front of a black standard adopted by various militant Islamist groups in this Instagram photo that was entered as evidence.
Prosecutors say Tsarnaev was a self-radicalized jihadist who pored over militant writings, including the article "How to Build a Bomb in the Kitchen of Your Mom." It was found on his laptop and other devices, part of a full-edition download of Inspire magazine, a glossy English-language propaganda tool put out by al Qaeda in the Arabian Peninsula.
This Russian manual on how to fire a handgun was found in the apartment where Tsarnaev's brother, Tamerlan, lived. Tamerlan Tsarnaev was killed in a shootout with police in Watertown, Massachusetts, on April 19, 2013.
This copy of The Sovereign, which calls itself the "newspaper of the resistance," was also found in Tamerlan Tsarnaev's apartment.
Pictured here is a box of bullets found on a street after the shootout in Watertown. The brothers' fingerprints were on the box, prosecutors said.
A pressure cooker was embedded in the side of a resident's Honda during the Watertown shootout.
Photos of the Watertown shootout were entered into evidence. Neighbors came to their windows and then retreated. One grabbed his infant son and headed toward the back of his house with his wife. Another grabbed a camera and took photographs from an upstairs window.
The Tsarnaevs had carjacked a Mercedes SUV in Watertown before the shootout. The vehicle was covered in bulletholes, and the rear window was shattered.
This unexploded pipe bomb was found at the scene of the shootout between police and the Tsarnaev brothers in Watertown.
Prosecutors said these boards were attached to the boat where police found Dzhokhar Tsarnaev hiding. A carved message reads, "Stop killing our innocent people and we will stop."
Prosecutors say this surveillance image shows Tsarnaev visiting an ATM hours before a police chase and chaotic shootout in which more than 200 rounds were fired.
Another view of Tsarnaev's visit to the ATM.
Exhibits related to the shooting death of
MIT Officer Sean Collier were introduced to the jury on Wednesday, March 11. This image from the crime scene appears to show a bloody gun.
This burned tank top and yellow hoodie belonged to bombing survivor Jessica Kensky.
Prosecutors say this Fox Racing logo was from one of the backpacks containing a bomb.
Prosecutors say this still image from surveillance video shows Tsarnaev in the UMass Dartmouth gym the day after the bombings.
Prosecutors showed the jury photos of what they say are Tsarnaev's writings inside the boat he was captured in.
This image is from a surveillance camera outside the Forum restaurant in Boston's Copley Square just after the bombing.
Prosecutors presented two Twitter accounts linked to Tsarnaev that, they said, showed targeting the marathon had been on his mind for at least a year. One account, @J_tsar, contained 1,100 tweets and was the more mainstream of the two. On the day of the 2012 Boston Marathon, a tweet from the account read, "They will spend their money & they will regret it & they will be defeated."
Prosecutors said the second Twitter account is evidence that Tsarnaev led a double life. By day, he was a slacker college sophomore. By night, he was a wannabe jihadist, posting on the account @Al_firdausiA. In one tweet, he urged people to listen to radical cleric Anwar al-Awlaki's lectures. "You will gain an unbelievable amount of knowledge," he said in March 2013, just weeks before the bombings. Prosecutors also allege in an indictment that Tsarnaev downloaded al-Awlaki's writings, calling him a "well-known al Qaeda propagandist." Al-Awlaki had been killed in a U.S. drone strike in 2011.
A Boston Marathon bombing victim is tended to in the street.
Victims at the finish line just after the bombing.
A closer view of 8-year-old Martin Richard in the crowd before the bombing.
Boston police tend to a wounded child. CNN has chosen not to show the young victim's face.
Mayhem along Boylston Street.
Bleeding, he picked up a pencil and wrote what Assistant U.S. Attorney William Weinreb called his "manifesto."
Tsarnaev wrote he was jealous that his brother, Tamerlan, had achieved paradise by dying like a holy warrior; he was killed the night before during a gunbattle with police. The indictment against him says Tsarnaev helped in his brother's demise by running him over and dragging him along the road as he tried to run down police.
About the bombings, Tsarnaev wrote on the boat that he didn't enjoy killing innocent civilians, but that circumstances excused it.
"The US Government is killing our innocent civilians but most of you already know that," he wrote. "Know you are fighting men who look into the barrel of your gun and see heaven, now how can you compete with that. We are promised victory and we will surely get it."
Streaks of blood cover portions of his message. More than a dozen bullet holes obliterate parts of words. So ended one of the biggest manhunts in U.S. history.
While in the boat, he wrote that he couldn't stand to see the U.S. government "go unpunished" for killing Muslims. "We Muslims are one body, you hurt one you hurt us all."
He ended with: "Now I don't like killing innocent people it is forbidden in Islam but due to said " -- the word was lost to a bullet hole -- "it is allowed."
Tsarnaev's connections: Who's who
Judge George O'Toole viewed the boat Tuesday afternoon so he could rule on a defense request to show the entire boat "in context" to the jury. He turned down requests by the media to accompany him.
The defense said the government only presented about 45 tweets out of about 1,100. Many were benign, about girls, cars and food as well as sleeping and disliking studying, the defense argued.
On Monday, FBI agent Steven Kimball testified about two Twitter accounts used by Tsarnaev. One account shows he tweeted on the day of the April 15, 2013, bombing:
"Ain't no love in the heart of the city, stay safe people"
His last tweet was on April 17. He sent it while on the run:
"I'm a stress free kind of guy"
His other account carried seven tweets, including this:
"strive to be a better muslim, be greedy with your time, devote most of it to the Almighty for it is his satisfaction that you need #islam"
Photos: Manhunt for Boston bombers
Boston bombing suspect Dzhokhar Tsarnaev is detained by officers on Friday, April 19. After a car chase and shootout with police, one suspect in the Boston Marathon bombing, Tamerlan Tsarnaev, was shot and killed by police early Friday, and his brother and second suspect, Dzhokhar Tsarnaev, was taken into custody Friday night. The two men are suspects in the bombings at the Boston Marathon on April 15, that killed three people and wounded at least 170.
See all photography related to the Boston bombings.
Special imaging techniques employed by Massachusetts State Police reveal Boston Marathon bombing suspect Dzhokhar Tsarnaev hiding in a boat in a backyard in Watertown on April 19.
Dzhokhar Tsarnaev gets out of the boat he was hiding in outside of a home in Watertown, as seen in a surveillance video still.
An ambulance carries Boston Marathon bombing suspect Dzhokhar Tsarnaev, 19, from the scene after he was apprehended in Watertown, Massachusetts, on April 19.
Police SWAT teams leave the area after apprehending the suspect in a yard where he was hiding in a dry-docked boat on April 19.
Residents flee from an area where a suspect was hiding on Franklin Street on April 19.
SWAT team members run toward a police assault on a house as gunfire erupts on April 19.
People react while watching police respond to reported gunfire on April 19.
SWAT team members move down residential streets as they perform door-to-door searches in Watertown, Massachusetts, on April 19.
A U.S. military helicopter lands behind Watertown Mall as law enforcement agencies continue to search for the 19-year-old bombing suspect on Friday.
SWAT teams prepare to enter a home as they continue the door-to-door search.
U.S. President Barack Obama meets with members of his national security team in the Situation Room of the White House on April 19 to discuss developments in the Boston bombings investigation.
SWAT team members line a residential street in Watertown, Massachusetts, as the manhunt continues on Friday.
A man watches from the window of a home as a SWAT team member keeps watch on Friday, in Watertown, Massachusetts.
Police to continue to the door-to-door search on Francis Street in Watertown, Massachusetts, on Friday.
Law enforcement officers place themselves in an overhead position on Arsenal Street as the search continues on April 19.
Law enforcement officers react to what was initially thought to be a threatening suspect on Arsenal Street on April 19.
A police SWAT team searches houses on April 19 for the second suspect.
SWAT teams searches homes along Winsor Avenue in Watertown on April 19.
A Massachusetts state trooper watches other troopers line up at Watertown Mall as the manhunt for the second suspect continues in Watertown on Friday.
Police continue the ongoing manhunt for the second suspect on Williow Avenue in Watertown on Friday.
A Watertown police vehicle with bullet holes in its body and a shattered windshield is towed out of the search area on April 19 in Watertown, Massachusetts.
A Massachusetts State Police officer checks the bag of a cyclist amid heightened security on Friday in Watertown.
Katia Costa looks out her window as police continue the manhunt on Nichols Avenue in Watertown on Friday.
Ruslan Tsarni, uncle of the Boston terror suspects, told
CNN affiliate WBZ that Tamerlan "got what he deserved" in an interview outside his home in Montgomery Village, Maryland, on Friday.
A woman is questioned by Cambridge police and other law enforcement agencies Friday near the home of the second suspect in Cambridge, Massachusetts. A Massachusetts Institute of Technology campus police officer was shot and killed late Thursday night at the school's campus in Cambridge. A short time later, police reported exchanging gunfire with alleged carjackers in nearby Watertown.
SWAT teams move into position at the intersection of Nichols and Melendy avenues in Watertown, Massachusetts, on Friday.
SWAT teams gather at the intersection of Nichols and Melendy avenues in Watertown while searching for the remaining suspect on Friday.
Onlookers take pictures while SWAT team members look around on Friday.
Massachusetts Gov. Deval Patrick, left, speaks to the media at a shopping mall on the perimeter of a locked-down area during the search on Friday.
Metro SWAT members hang off the back of a truck during the search on Friday.
SWAT officers check a door with guns ready on Friday.
Officers patrol Watertown on Friday.
The aftermath of the shootout that police said involved the two suspects in Watertown early Friday.
Police with guns drawn search for a suspect on Friday in Watertown, Massachusetts.
A police officer runs with his gun drawn on Friday.
Boston Police gather in the parking lot in front of a Best Buy store near the Watertown Mall on Friday.
Boston Police Commissioner Edward Davis speaks during a media briefing in the parking lot of the Watertown Mall on Friday.
Boston police gather in front of a Best Buy on Friday.
Police stop cars at School and Walnut streets on Friday.
A Massachusetts state trooper checks a building along Mount Auburn Street as police search neighborhoods in Watertown.
Police search neighborhoods yard by yard on Friday.
Police convene on School and Walnut streets on Friday.
A police officer talks to a driver at a checkpoint in Watertown, Massachusetts.
The jury also has now seen Tsarnaev in videos, trailing his brother onto Boylston Street. Both carried heavy backpacks. He paused for four minutes, standing next to a tree in front of the Forum restaurant. In front of him stood a line of children who were leaning over the barricade and watching the race. He put his backpack down at his feet and made a phone call.
Timeline of the bombings, manhunt and aftermath
When his brother's bomb went off a block away, heads swiveled in surprise in the direction of the noise. And there was Tsarnaev walking through the crowd, looking back over his shoulder as his own bomb went off 12 seconds later. Martin Richard, an 8-year-old standing in the line of kids, took the full brunt of the blast, which tore him apart.
The bombs went off at 2:49 and 2:50 p.m., about the same time as he exchanged phone calls with his brother. The next video showed Tsarnaev in the crowd running. Other videos show him carrying on as usual: buying milk and swiping his card at his college gym. But FBI agents were already in pursuit, collecting store security videos and looking for somebody suspicious in the marathon crowd.
By Wednesday night, authorities had a good idea who they were looking for. By Thursday night, his photo had been released to the public. By the next morning, his brother was dead, and Tsarnaev was hiding in the boat, writing of martyrdom and paradise.
Boston bomber Dzhokhar Tsarnaev
Dzhokhar Tsarnaev was arrested on April 19, 2013, after a massive manhunt. An overnight shootout with police killed the other suspect -- Tsarnaev's 26-year-old brother, Tamerlan. A jury condemned Tsarnaev to death on Friday, May 15, for his role in killing four people and wounding hundreds more.
On April 18, 2013, the FBI released photos and videos of two suspects and asked the public to help identify them.
Dzhokhar Tsarnaev was found on April 19, 2013, in a boat that was dry-docked in the backyard of a Watertown home. He was covered in blood from bullet wounds.
Tsarnaev stands in court, flanked by his lawyers, in this sketch from July 2013.
An image posted to the social sharing website Reddit purportedly shows Dzhokhar Tsarnaev being detained by law enforcement officers.
Tsarnaev was seen on this convenience store surveillance video that was released by the Boston Police Department.
A still of the suspects from footage released by the FBI after the bombing.
Additional photos and video were released by the FBI.
A picture of Tsarnaev from his apparent profile on VKontakte, a Russian social network similar to Facebook.
The Boston Police Department also released this undated photograph of Tsarnaev.