Story highlights Bombing victim: Dzhokhar Tsarnaev deserves the death penalty

Prosecutors argue Tsarnaev acted in a "depraved manner," lacks remorse

Tsarnaev's mother: "We are ... sickened about our child"

Toobin: Defense will weigh whether to ask for change of venue

Federal prosecutors say they'll seek the death penalty against Boston Marathon bombing suspect Dzhokhar Tsarnaev, arguing that he acted in "an especially heinous, cruel and depraved manner" and lacks remorse.

The highly anticipated announcement Thursday means that when the case against Tsarnaev goes to trial, jurors will not only weigh whether he's guilty, but also whether he deserves to die.

For Liz Norden, it's one small step forward.

Her sons, JP and Paul, each lost a leg in the bombings, which killed three people and injured more than 250 at the April 15 race.

"I just am relieved that it's going forward in the right direction, one step forward in the recovery process, just that the option is out there on the table for the jurors, if that's the way it goes," she told CNN's The Situation Room.

Whenever the case goes to trial, Norden said she plans to attend every day.

"It's important to me. I'm trying to make sense of what happened that day. My boys went to watch a friend run the marathon, and one came home 46 days later. The other one, 32 days later. And their lives are forever changed," she told CNN's Wolf Blitzer. "So I want to try and find out, somehow, to make some sense of how somebody could do this to all these innocent people."

Attorney general: Harm caused was factor

Authorities allege Tsarnaev, a Chechnya-born American, and his brother Tamerlan planted two homemade bombs near the finish line of the marathon, then killed a Massachusetts Institute of Technology police officer three days later.

The attacks triggered the massive manhunt that led to Tsarnaev's capture. Police shot and killed Tamerlan Tsarnaev during the manhunt.

"The nature of the conduct at issue and the resultant harm compel this decision," U.S. Attorney General Eric Holder said in a statement released by the Justice Department Thursday announcing that prosecutors would pursue the death penalty in the case.

After Holder made his decision , prosecutors filed a notice listing factors that they argue justify a death sentence in the case. Among them: The attack killed multiple people, involved substantial planning and premeditation and involved betrayal of the United States, prosecutors said.

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Photos: Photos: Suspects tied to Boston bombings Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Dias Kadyrbayev, left, with Boston Marathon bombing suspect Dzhokhar Tsamaev in a picture taken from the social media site VK.com. Kadyrbayev is expected to plead guilty August 21 to charges in connection with removing a backpack and computer from Tsamaev's dorm room after the April 2013 bombing, according to a defense lawyer. Hide Caption 1 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Bombing suspect Tamerlan Tsarnaev was killed during the shootout with police in Watertown, Massachusetts, on April 19, 2013. He is pictured here at the 2010 New England Golden Gloves. Hide Caption 2 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Dzhokhar Tsarnaev was captured in a Boston suburb on April 19, 2013, after a manhunt that shut down the city. In July, he pleaded not guilty to killing four people and wounding more than 200. Hide Caption 3 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – From left, Azamat Tazhayakov and Dias Kadyrbayev went with Boston bombing suspect Dzhokhar Tsarnaev to Times Square in this photo taken from the social media site VK.com. A federal grand jury charged Tazhayakov and Kadyrbayev with obstructing justice and conspiracy to obstruct justice relating to the removal of a backpack from Tsarnaev's dorm room after the bombings. Tazhayakov was convicted of conspiracy and obstruction charges in July 2014. He faces up to 25 years in prison at his sentencing in October. He has filed an appeal. Hide Caption 4 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Robel Phillipos, a U.S. citizen, was also arrested on May 1, 2013 . He was charged with lying to federal agents about the bombing, according to court papers. Hide Caption 5 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Phillipos, Tazhayakov and Kadyrbayev are accused of removing items from Tsarnaev's dorm room after the bombings on April 15, 2013. The items they took included a backpack containing fireworks that had been "opened and emptied of powder," according to the affidavit. Hide Caption 6 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – The FBI released photos and video on April 18, 2013, of two men identified as Suspect 1 and Suspect 2 in the deadly bombings at the Boston Marathon. They were later identified as Dzhokhar Tsarnaev, 19, and his brother Tamerlan Tsarnaev, 26. Hide Caption 7 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Boston Police released surveillance images of Dzhokhar Tsarnaev at a convenience store on April 19, 2013. Hide Caption 8 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – The FBI tweeted this photo on April 19, 2013, and urged Watertown residents to stay indoors as they searched for the second suspect. Hide Caption 9 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – The FBI released photos and video on April 18, 2013, of two men it called suspects in the deadly bombings and pleaded for public help in identifying them. The men were photographed walking together near the finish line. Hide Caption 10 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – A man identified as Suspect 2 appeared in this photograph by bystander David Green, who took the photo after completing the Boston Marathon. Green submitted the photo to the FBI, he told Piers Morgan in an interview. Hide Caption 11 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – The man identified as Suspect 2 appears in a tighter crop of David Green's photo. Hide Caption 12 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Authorities later identified Suspect 1 as Tamerlan Tsarnaev. Hide Caption 13 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Suspect 2 was identified as Dzhokhar Tsarnaev. Hide Caption 14 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Suspect 1 walks through the crowd. Hide Caption 15 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Suspect 1 walks through the crowd. Hide Caption 16 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Suspect 1 walks through the crowd. Hide Caption 17 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Both suspects are seen walking through the crowd. Hide Caption 18 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Suspect 2 walks through the crowd. Hide Caption 19 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Suspect 2 walks through the crowd. Hide Caption 20 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – A photo released by the FBI highlights Suspect 2. Hide Caption 21 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – A photo released by the FBI highlights Suspect 2. Hide Caption 22 of 23 Photos: Photos: Suspects tied to Boston bombings Suspects tied to Boston bombings – Suspect 2 walks through the crowd. See all photography related to the Boston bombings. Hide Caption 23 of 23

Photos: The arrest of Dzhokhar Tsarnaev Photos: The arrest of Dzhokhar Tsarnaev The backlash over Rolling Stone's cover photo of Boston Marathon bombing suspect Dzhokhar Tsarnaev led to the release of new photos of his capture. The images, released by Police Sgt. Sean Murphy on July 18, 2013, show Tsarnaev as he emerges from the boat where he hid in Watertown, Massachusetts. Hide Caption 1 of 5 Photos: The arrest of Dzhokhar Tsarnaev Tsarnaev was found in a motorboat dry-docked in the backyard of a Watertown home on April 19, 2013. Hide Caption 2 of 5 Photos: The arrest of Dzhokhar Tsarnaev "This guy is evil," Murphy said. "This is the real Boston bomber. Not someone fluffed and buffed for the cover of Rolling Stone magazine." Tsarnaev has pleaded not guilty to 30 federal charges related to the marathon bombings. Hide Caption 3 of 5 Photos: The arrest of Dzhokhar Tsarnaev Tsarnaev exits the boat during his capture. The pictures were taken by Murphy and published online by Boston Magazine. Hide Caption 4 of 5 Photos: The arrest of Dzhokhar Tsarnaev Police tend to Tsarnaev after his detainment. Hide Caption 5 of 5

Dzhokhar Tsarnaev is charged with 30 federal counts stemming from the attack. He has pleaded not guilty to all charges.

The decision announced Thursday is no surprise, CNN senior legal analyst Jeffrey Toobin said.

"This is a case, that, if you believe in the death penalty, seems to cry out for the death penalty, even though the defendant is only 19 years old, and potentially the junior partner to his late brother," Toobin said.

But that doesn't mean it's an open-and-shut case.

"One of the most interesting, difficult, strategic decisions the defense faces," Toobin said, is whether to push for a change of venue for the trial.

"Boston was obviously deeply traumatized by this incident. And the jury pool is Boston, if the case remains where it is. But Boston is also probably the most liberal city in the country. Death penalty opposition there is higher than anywhere else," Toobin said. "So does the defense go somewhere else, where people don't have the immediate association with the crime? Or do they go somewhere that might not oppose the death penalty in the same numbers?"

Massachusetts abolished the death penalty three decades ago, but prosecutors can seek the death penalty against Tsarnaev because federal law allows for the penalty in certain circumstances.

Despite Holder's decision to authorize the death penalty in the Tsarnaev case, prosecutors still could reach a plea deal for a lesser sentence with his attorneys, who include death penalty lawyer Judy Clarke.

Survivor speaks out

Federal officials weighed a number of factors before they announced their decision, including the opinions of victims of the deadly attack.

Survivors were asked to fill out a questionnaire about what they thought about the death penalty.

Marc Fucarile, who lost a leg in the bombing, said he has no doubt about where he stands: Tsarnaev deserves to die.

"I prefer the death penalty, because I prefer that people know that if you terrorize our country, you're going to be put to death," he told CNN affiliate WCVB . "And I strongly believe that's how it should be."

Life since the bombing hasn't been easy, he said.

"This is almost kind of too easy for him (Tsarnaev)," Fucarile told WCVB. "I still haven't walked for more than day in a prosthetic, and it's almost a year later. ... Life's good, you know. It's going to get better, but it's going to be a road, and it's going to be a long road for the rest of our lives."

In a statement Thursday, Gov. Deval Patrick urged the state's residents to stay strong.

"One way or another, based on the evidence, Tsarnaev will die in prison. In each milestone of the case -- today's announcement, the trial and every other significant step in the justice process -- the people hurt by the Marathon bombings and the rest of us so shocked by it will relive that tragedy," he said. "The best we can do is remind each other that we are a stronger Commonwealth than ever, and that nothing can break that spirit."

Victims' mom: 'It shouldn't have happened'

Tsarnaev's attorney did not immediately respond to a request for comment.

Reached before federal authorities announced their decision to seek the death penalty, Zubeidat Tsarnaev, the suspect's mother, did not comment on the specifics of the case.

"We are, you know, sickened about our child. ... We have nothing in our heads or in our hearts, so what should I say? We are just really sick," she told CNN's Nick Paton Walsh in a telephone interview.

"The only thing I want to say," she said, "is I want the whole world to hear that I love my son, my precious Dzhokhar. That's it."

Thousands of miles away, another mother -- Norden -- said her love for her own sons makes her want to learn more about Dzhokhar Tsarnaev during the trial, to try to understand why the deadly attacks occurred.

"I watch my sons, and it's sad. Their lives have changed, and they're OK with it. They've learned to accept it. But I can't," she said, her voice cracking. "You know, those are my kids, and they went to watch a marathon on the streets of Boston, and it shouldn't have happened."