Marathon bombing victim Krystle Campbell was the “light of her father’s life,” prosecutor Steve Mellin said during closing arguments in the penalty phase of the Dzhokhar Tsarnaev trial Wednesday. 
 
 “Now,” Mellin said, “that light is out.” 
 
 At any point before those two bombs exploded at the finish line on that beautiful Patriots’ Day, Tsarnaev “could have reflected, reconsidered, and stood down” from the destruction he and his brother had planned for months, he said 
 
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 Instead, Mellin said, Tsarnaev walked up behind a group of children, placed a backpack four feet behind them, and waited. Mellin paused for 20 seconds during his argument — and then told the jury that Tsarnaev waited 12 times that before walking away. 
 
 “The defendant knew what kind of hell was going to happen, that he unleashed,” he said. 
 
 That hell encompassed more than the pain the dead and wounded suffered, Mellin said. It’s the torment the survivors still feel, the families — like the Richards and the Corcorans — that were physically and emotionally “blown apart” by the events of that day. 
 
 Mellin denounced the defense team’s assertion that Tsarnaev was under his older brother Tamerlan’s sway: “Tamerlan Tsarnaev was not the defendant’s master. They were partners in crime and brothers in arms. Both decided they wanted to punish America, in a way that would win them glory and a place in paradise.” 
 
 The brothers targeted Patriots’ Day, a day in which they knew families would gather to watch the marathon, in which the world would be watching, Mellin said, and targeted innocent people. 
 
 Tsarnaev has been remorseless all along, Mellin said, buying milk right after the bombings and flipping off his holding cell’s camera months later. 
 
 “The only sentence that will do justice in this case is a sentence of death,” he said. 
 
 But in her closing argument, defense attorney Judy Clarke said the death penalty is reserved for the worst of the worst—and “Dzhokhar Tsarnaev is not the worst of the worst.” 
 
 Clarke spent much of her argument going through the circumstances that brought Tsarnaev into the plot she said originated with Tamerlan. 
 
 “The story of the Boston Marathon bombing is of a tragedy of their making, but it is more than that,” she said. 
 
 Clarke detailed Tsarnaev’s family life, from the many moves he went through as a child to his troubled parents and status as “the invisible kid,” and, finally, Tamerlan’s influential personality and radical beliefs crystallized during his 2012 trip to Russia. 
 
 “To say Tamerlan did not influence Dzhokhar defies the reality,” Clarke said, adding that, by September of 2012, Dzhokhar’s “sole source of family, of support, of strength, was his older brother.” 
 
 Tamerlan was the one who sought jihad in Russia, who sent radical Islamist materials to Dzhokhar, who had a photograph of dead children as his computer’s wallpaper, she said. 
 
 “Dzhokhar would never have done this, but for Tamerlan,” Clarke said. 
 
 According to Clarke, the government failed to prove that Dzhokhar is a hopeless case for whom the only appropriate punishment is death. According to the testimony of Sister Helen Prejean, he has even grown to show remorse for his crimes, she said. 
 
 “We think we’ve shown you that … Dzhokhar has potential for redemption,” Clarke said. 
 
 Should Tsarnaev be spared, she said, it’ll be no picnic. He’ll be sent to ADX, where Clarke said “he’ll have no glory and stature that martyrdom could bring.” 
 
 Clarke emphasized that no punishment could take back what Tsarnaev did, or even “balance the scales.” Life is prison is not a lesser punishment than death, she said—it’s just another kind. 
 
 “I ask you to make a decision of strength,” she told jurors. “I ask you to choose life.” 
 
 During his rebuttal, prosecutor William Weinreb criticized the defense’s continued focus on Tamerlan: “At times it might have seemed to you that Tamerlan was on trial.” 
 
 But at no point in the trial, Weinreb said, did the defense prove that Tamerlan made his brother commit any crimes, or brainwashed him to hold any radical beliefs. 
 
 Instead, Tsarnaev’s “actions are the best guide to the depths of his beliefs,” he said. 
 
 Despite defense testimony that Tsarnaev feels remorse, Weinreb said that it is unlikely that Tsarnaev would spend much time thinking about the bombing victims should he be sent to prison for life. 
 
 “Maybe he’ll leave behind his memories of Martin, Lingzi and Krystle the same way he left them lying on the street, bleeding,” he said. 
 
 “The defendant deserves the death penalty not because he’s inhuman,” Weinreb said, “but because he’s inhumane.” 
 
 Referring to life in prison as the minimum allowable punishment for Tsarnaev’s crimes, Weinreb asked jurors, “Does he deserve the minimum punishment, or do these crimes, these four deaths, deserve something more?” 
 
 It was the government’s last line to the jury, who are now tasked with determining Tsarnaev’s fate. 
 
 Read past daily summaries from the trial. 
 
 The Alcatraz of the Rockies 
 
 Previous -- of -- Next Dubbed the “Alcatraz of the Rockies,” ADX Florence is the super-maximum-security federal prison in Florence, Colorado where Dzhokhar Tsarnaev could spend the rest of his life if he does not recieve the death penalty. BOB DAEMMRICH/AFP/Getty Images 
 
 Previous -- of -- Next “There have been some reports that the conditions at Guantanamo are better than at the ADX,” Laura Rovner, associate law professor at the University of Denver College of Law, told The Boston Globe CHRIS MCLEAN/AP Photo 
 
 Previous -- of -- Next Cells at ADX are fitted with immovable concrete furniture. US District Court, Colorado via The Boston Globe 
 
 Previous -- of -- Next Tsarnaev would have access to a small outdoor cage for exercise and fresh air for one hour a day. US District Court, Colorado via The Boston Globe 
 
 Previous -- of -- Next Seven inmates have reportedly committed suicide since the prison opened in 1994. A class-action lawsuit was filed in 2012 alleging the prolonged solitary confinement at the prison constitutes cruel and unusual punishment. US District Court, Colorado via The Boston Globe 
 
 Previous -- of -- Next Advertisement 
 
 Previous -- of -- Next Terry Nichols, one of the accomplices in the Oklahoma City bombing, is an inmate at ADX serving 168 consecutive life sentences. REUTERS/Staff/Files 
 
 Previous -- of -- Next Ted J. Kaczynski, commonly known as the Unabomber, is also an inmate at ADX. Lewis and Clark Sheriff's Department/Associated Press 
 
 Previous -- of -- Next During the trial’s sentencing phase, Tsarnaev’s defense team called Mark Bevy, a former prison warden, to the stand to describe how bleak Tsarnaev’s life would be at ADX. On cross-examination, prosecutors downplayed Bevy’s previous testimony, explaining that Tsarnaev would be able to write letters, have visitors, and even author a book while in prison. Federal Public Defender Office 
 
 Previous -- of -- Next A photo of ADX from above submitted into evidence by Tsarnaev’s defense team. Federal Public Defender Office 
 
 Follow live updates from reporters at the trial below. 
 
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 The Charges Against Dzhokhar Tsarnaev Explained in Plain English 
 
 Map: Important Boston Marathon Bombing Locations 
 
 Timeline of Boston Marathon Bombing Events ||||| The chief of the MIT police on Wednesday recalled the last time he saw Officer Sean Collier alive — telling him to "be safe" shortly before authorities say he was killed by the Boston Marathon bombers. 
 
 Chief John DiFava testified for the government at the trial of Dzhokhar Tsarnaev. He told the jury that he was leaving campus on the night of April 18, 2013, and spotted an MIT car on the street. 
 
 "I always make it a point to say hello," the chief testified. "I chatted with him for a few minutes. I told him to be safe, and I left." 
 
 He put the conversation at about 9:35 p.m., less than an hour before authorities have said Collier was shot to death in his patrol car. Three people were killed and more than 260 injured in the marathon bombings three days earlier. 
 
 Tsarnaev's lawyers have conceded that he took part in the bombings but say he was influenced by his older brother, Tamerlan, who authorities say was killed in the brothers' getaway attempt. 
 
 Sgt. Clarence Henniger of the MIT police described finding Collier in his cruiser, covered in blood, and telling him, "Hang in there, just hang in there." Jurors heard Henniger scream into his radio for medical help: "Get on it!" 
 
 A Cambridge police detective, Brendan O'Hearn, described performing chest compressions, trying in vain to save Collier's life. 
 
 Jurors on Wednesday also saw the tattered pieces of a backpack that Dzhokhar Tsarnaev may have used to carry one of the make-shift bombs. FBI Special Agent Sarah De Lair held up pieces of the black and white backpack for the jury, saying they were found near the Forum restaurant. 
 
 Dzhokhar Tsarnaev, now 21, faces the possibility of the death penalty if convicted. 
 
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– Jurors in the trial of Dzhokhar Tsarnaev heard about the murder of MIT police officer Sean Collier today, along with his chief's final exchange with him. As Chief John DiFava was leaving the campus, he spotted Collier's cruiser, reports NBC News. "I always make it a point to say hello," says the chief. "I chatted with him for a few minutes. I told him to be safe, and I left." That took place about 9:30pm on April 18, 2013. Less than an hour later, Collier was shot to death in his car, allegedly by the Tsarnaev brothers as they unsuccessfully tried to steal his gun. Video footage from the scene shows two men approaching Collier's car and his brake lights flickering, reports the Boston Globe. Then one of the two men extends an arm as a muzzle flashes and a bicyclist rides by. The latter appears to have been graduate student Nate Harman, who testified today that he was riding home and made eye contact with one of the two men by the car. Harman identified him as Dzhokhar Tsarnaev. (Previously, jurors got a close look at Tsarnaev's written messages inside the boat where he was hiding.)