13th Juror: Indelible images, searing words in Boston

Boston (CNN)We've seen one haunting image after another: Bombs go off, the wounded bleed and crawl in the street. The suspect lurks in the crowd with a heavy backpack, and then runs away without it. A pool of blood, almost too brightly red, widens under the driver's side seat of a police car. A frantic man jumps out of an SUV and runs for his life.

Fifty witnesses have told their stories at the Boston Marathon bombing trial; each is difficult to hear and impossible to forget.
The 13th Juror

No cameras are allowed at the Tsarnaev trial. But CNN's Ann O'Neill will be there every day. Think of her as The 13th Juror, bringing insights here weekly. And follow @AnnoCNN on Twitter daily.

The images and voices, coming one right after another, can turn your stomach and break your heart. Each afternoon ends with a powerful flourish that leaves plenty to think about after the courtroom doors fling open, returning everyone to their normal lives.
Normal is a relative term here. Anyone who witnesses this trial will be changed by the devastation they see -- just as so many lives were changed by the bombings.
    The bombs found people who weren't just alive, they were consuming their lives, living out loud. They are active people who run and ski and hike and camp and do all the things that get you out of the house and out there in the world. They included nurses, students and families engaged in the city where they lived. They were Marathon fans.
    The ones who survived walk into court on gleaming prostheses or are pushed inside in wheelchairs. That is their new normal and most of them don't hesitate to look in the direction of Dzhokhar "Jahar" Tsarnaev, the young man who did this to them.
    He doesn't deny he was there. But he has yet to own up to what he has done. He looks away, slumping in his chair as if he's desperate to make himself smaller. If he could, no doubt he'd become invisible.
    Jurors and spectators will gasp, sniffle and dab their eyes at this overwhelming story of human pain and survival. But not Tsarnaev. He slouches and fiddles with pens and post-its.
    MIT Police Chief  John DiFava
    He seems to be the only person in the courtroom who isn't haunted.
    Who could forget these voices and images?
    Pass by an REI store or hop on the T behind somebody wearing a North Face jacket and Jessica Kensky comes to mind. She's having a hard time getting around this winter; in January she had to give up her second leg.
    In court, she held up a yellow jacket, which she joked was "overpriced." It's what she was wearing when the bombs went off on Marathon Monday. It is bloodstained and the back is tattered and charred.
    Everything changed in a flash.
    "I remember being happy, I remember feeling sunlight on my face. I remember feeling free." She felt the explosion rather than seeing it or hearing it.
    "I just felt like I was on a rocket."
    Kensky saw smoke and blood everywhere and felt like she was in war zone. She "went into nurse mode" and was so busy helping others, she didn't realize that she was on fire herself.
    She lost one of her legs within a day or two of the bombing. She fought hard to save the other for nearly two years because she couldn't bear the thought of being a double amputee.
    Prosecutor Steve Mellin, left, with Dr. Rene Robinson
    "I wanted to paint my toenails and put my feet in the sand. I wanted all of those things, and to lose my second leg was a gut-wrenching decision," she said. "It's just incredibly unnatural to make a decision to remove a body part -- and that if you can actually do that, you can improve your quality of life."
    Dr. James Bath jumped into the chaos, too, quickly changing roles from marathon bystander to first responder. He left us with this indelible memory:
    "Certainly, there were parts of limbs. There was a lot of burnt clothing and tissue. When I went into the Forum I noticed there was a young woman and a gentleman lying on the stairs. She was lying on top of him. Her foot had been sheared off. The gentleman she was with had the wherewithal to tourniquet off the leg. He kept saying he was saying he was sorry he brought her to the Marathon, and she was saying it's alright."
    He remembers seeing two young Asian women, one beyond help. Lingzi Lu, whose leg was sliced from ankle to hip, pressed her hands to her face and bled out. Her friend, Danling Zhou, had no idea she was so badly hurt. She was preoccupied with holding her own internal organs inside her body:
    "I remember I wake up laying on the fence, and there's smoke everywhere. I can't hear anything at that point. I saw blood all over the ground. I remember there is a man who used to be standing right in front of me. At that point he is sitting down and turning his face to me, like in slow motion. I can see his face and it's very scared. I think he is yelling to me, but I can't hear. His leg is not there anymore."
    Within days, there would be another bloody crime scene, this time on the MIT campus in Cambridge. A lone cop was ambushed for his gun and a bicyclist pedaled by, not entirely aware at first of what he was seeing.
    MIT police dispatcher David Sacco was getting worried. He had been unable to raise Officer Sean Collier on his police radio or his personal cell phone. It was about 10:20 p.m., getting close to quitting time. He sent out another alert, but he still wasn't getting a response.
    Prosecutor Mellin, left, and Dzhokhar Tsarnaev, center foreground.
    "It became an amount of time that wasn't comfortable."
    Sgt. Clarence Henniger checked on his rookie officer.
    "When I arrived at the cruiser, I looked inside and that's when I observed a wound to the head, to the temple. I observed a wound to the neck and I observed a wound to his hand.
    A prosecutor asked, "Was there blood?"
    "Yes sir."
    "Where?"
    "All over his body."
    He got on the police radio: "Officer down! Officer down! Get me help! Officer down."
    And then he started to shout, fear and adrenalin in his voice: "Get on it!!!"
    "Get me an ambulance."
    Henniger and another officer removed Collier from his car, but it wasn't easy. "The amount of blood on his body made it difficult to get a grip on him."
    Collier, according to testimony, was shot six times at close range, including three shots to the head. One of the bullets entered between his eyes. The shots completely destroyed his brain.
    Dun Meng heard the sirens and saw the blue police lights flashing as officers from all over responded to the Collier shooting. He had pulled his black Mercedes SUV over to the side of the road to answer a text when a man tapped on his window. He though he was asking directions. Instead, he pulled a gun, hopped in the passenger seat and ordered Meng to drive.
    At first, Meng assumed he was just being robbed. He handed over his wallet and cash, but it wasn't much. His passenger was acting scary by now.
    "He pulled a magazine of the gun out to show me there is bullets in the gun. He told me, 'I'm serious so don't be stupid.' "
    "After that he asked me, 'Do you know the Boston Marathon explosion?' And then he asked, 'You know who did it?' He said, 'I did it and I just killed a policeman in Cambridge.' "
    Meng immediately remembered all the police cars he'd seen with lights flashing.
    "How did that make you feel," Assistant U.S Attorney Steve Mellin asked.
    "Terrified. The whole world is looking for him at the time."
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    Jahar Tsarnaev, who had been following in his green Honda, soon joined his brother and Meng in the car. Meng believed Jahar was armed as well, and gave him his ATM card and personal identification number.
    When the pair stopped for gas and snacks, Meng made a break for it.
    Jahar was in the store, and Tamerlan was studying a GPS device. There had been talk of driving to New York.
    "I think this is my best chance because there's only one of them in the car and the doors are unlocked," Meng said.
    "It was the most difficult decision of my life. I asked Tamerlan before, 'Are you going to kill me tonight?' He told me, 'I'm not going to kill you. Just relax, man.'
    "I was struggling with that. Should I trust him, or should I just take this chance myself and run away?
    "I count down -- 1,2,3,4 -- and I opened the car door quickly and successfully and dashed into the street. I could feel he was trying to grab me. I could feel his hand close to my left hand. I could feel wind."
    He ran across the street to a Mobil gas station and convenience store. He begged the clerk to call 911. He didn't look back.
    "I'm terrified. I feel if I don't look back, they won't follow me."
    It is Meng's story that will stick with the jury over the weekend. On Monday, testimony will likely move to the police chase and shootout in Watertown.
    There are four chapters to this story, as Assistant U.S. Attorney William Weinreb pointed out during his opening statement. They cover four crime scenes: The marathon finish line, the MIT campus where Collier was killed, the carjacking of Dun Meng, and Watertown, where Tamerlan Tsarnaev was killed in a gunbattle with police and Jahar was found hiding in a boat.
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    The fourth chapter will be as bloody and dramatic as the others. Prosecutors are expected to call a police officer who nearly became Victim No. 5. He was hit in the crossfire and almost bled out on the street in Watertown.
    Tamerlan Tsarnaev breathed his last in the final chapter, succumbing to his injuries from the police shooting. He became the fifth person to die, even if he doesn't make the prosecution's official death count. Prosecutors never count the bad guys among the victims.
    Tamerlan Tsarnaev was run down and dragged in the street by Meng's SUV as cops try to pull him out of the way. Jahar, they say, was at the wheel, trying to run down the cops. He ditched the SUV and ran into the night. He found a safe hiding spot in Bill Hennenberg's backyard, where a boat was dry-docked for the winter. He crawled under the tarp.
    While he was hiding, Jahar took up a pencil, writing a message on the sides of the boat that became pocked with bullet holes and streaked with blood:
    "I'm jealous of my brother who ha(bullet hole)ceived the award of Jannutul Firdaus (insahllah) before me. I do not mourn because his soul is very much alive. God has a plan for each person. Mine was to hide in this boat and shed some light on our actions ... "
    He might not have died a martyr, but he's the last man standing. If the jurors find him guilty of most of these crimes, it will be up to them whether he pays with his life.