Seven years later, the Boston Marathon bombing is once again sending shockwaves through the city.

Merida Arredondo had already been on edge all summer. Her husband, Carlos, has been stuck in Costa Rica for more than six months due to a coronavirus-related flight stoppage. Alone in her Massachusetts home, every loud noise has rekindled memories of that horrible day she has long sought to suppress.

“The recent fireworks in the community every night were tormenting me. They sounded like they were in my backyard," Arredondo said. "And then this happens.”

"This" is the monumental decision made Friday by a three-judge panel of the First Circuit U.S. Court of Appeals that reversed the death sentence of 27-year-old Dzhokhar Tsarnaev for his role in the 2013 Boston Marathon bombing. The court ordered a new penalty-phase trial to determine whether Tsarnaev should be put to death for the attack that killed three people and maimed and wounded more than 260 others.

Arredondo and her husband Carlos sat through the 2015 trial. Carlos is the man in an iconic photo wearing a white cowboy hat and pushing the shattered body of Jeff Bauman in a wheelchair, minutes after the bombs went off near the finish line.

Merida Arredondo said when she received word that the First Circuit had overturned Tsarnaev's death sentence, “First, I was just in shock. And then overwhelmed that the possibility of not just our family, but especially those who lost their loved ones and those who had the most serious injuries, would have to endure the trial again.”

Arredondo told WGBH News although she personally opposes the death penalty, she fears the impact on the victims and their friends and families of having to once again relive horrible moments during a new death-penalty trial.

These memories include the sounds of the bombs going off, the images of bodies lying in the streets, limbs blown off and mixed amongst the debris, and the week-long hunt for the Tsarnaev brothers.

Some of those images and sounds were discussed on social media by people who went on to become jurors in Tsarnaev's sentencing trial. The First Circuit federal appeals court concluded that Judge George O'Toole did not do enough to screen out of the jury pool those individuals who may have been influenced by everything they had seen and heard.

Former U.S. Attorney Carmen Ortiz, whose office oversaw the 2015 prosecution of Tsarneav, vehemently disagreed with that conclusion.

“The reality is that there's always more and more questions that can be asked in this particular process,” Ortiz said. "The issue is, has there been a sufficient probing of the jurors to determine that they can render a verdict without bias? ... The judge made the determination that the jurors would be impartial and would be fair.”

Robert Bloom, a professor of law at Boston College, said he agreed with Ortiz.

“Judge O'Toole tried very hard. And the government probably felt that he was doing a good job and it wasn't going to be appealable,” Bloom said.

But former federal Judge Nancy Gertner said the Tsarnaev case was problematic from day one and should have been moved to another venue.

During the pre-trial stage, lawyers for Tsarnaev argued that finding an impartial jury in Boston would be near impossible, given the publicity in the case. O'Toole denied a request to change the venue. Around that time, according to court documents, it was discovered that a juror had lied about not having posted to social media about the case. A tweet written by the juror was found that described Tsarnaev as “a piece of garbage.”

Gertner said she found it hard to believe that O'Toole did not replace her and two other jurors when their social media postings were discovered, given that the defendant’s life was at stake.

"This was a singularly extraordinary thing to have happened in any case," Gertner said, "but especially a death penalty case, when you have a juror who lied in answer to a question. In my view, that would have been enough to tip any verdict at any time.”

During arguments by the government and the defense in December, the three appellate judges appeared skeptical about O'Tooles' responses to the social media postings. One of the judges, O. Rogeriee Thompson, asked the government lawyer, “Why isn't this this the kind of case that would require probing that kind of information?”

The appellate court last week concluded that the “bone-chilling still shots and videos” of the bombing required O'Toole to run a jury selection process “sufficient to identify prejudice,” but he did not.

Bloom said the government now has one of two choices it will likely pursue. “First, they could appeal it to the Supreme Court," Bloom said. "And if they are successful in that appeal, then death penalty, of course, would be reinstated. Or they could not appeal it and just have another penalty phase of the trial.”

With the Supreme Court session concluded for the season, a hearing would not occur until sometime in 2021, at the earliest. U.S. Attorney Andrew Lelling has not signaled how he will proceed, but Attorney General William Barr reopened the door to federal executions at the start of his tenure. Legal experts expect the government to move to retry the death penalty sentencing, but that may depend on whether President Donald Trump is re-elected given the time constraints.

Bloom said he hopes the government opts not to retry the case, for the sake of Tsarnaev’s victims and Boston itself.

“They don't want to keep hearing about Tsarnaev," Bloom said. "The marathon story turned into heroism, courage. Some of these victims made remarkable recoveries. The medical institutions were fabulous. I mean, why do we have to hear the horrors of it as opposed to 'Boston Strong?'”

Tsarnaev, 27, is confined to single cell at a super-maximum-security prison in an isolated section of Colorado, high in the Rocky Mountains. Bloom said staying in that cold, brutal environment the rest of his life should be punishment enough.

But some survivors of Tsarnaev’s carnage do not agree, and believe the man known as the Boston Marathon Bomber should pay the ultimate price.