A federal appeals court Friday threw out Dzhokhar Tsarnaev’s death sentence in the 2013 Boston Marathon bombing, saying the judge who oversaw the case did not adequately screen jurors for potential biases.

A three-judge panel of the 1st U.S. Circuit Court of Appeals ordered a new penalty-phase trial on whether the 27-year-old Tsarnaev should be executed for the attack that killed three people and wounded more than 260 others.

“But make no mistake: Dzhokhar will spend his remaining days locked up in prison, with the only matter remaining being whether he will die by execution,” Judge O. Rogeriee Thompson wrote in the ruling, more than six months after arguments were heard in the case.

An attorney for Tsarnaev said they are grateful for the court’s “straightforward and fair decision: if the government wishes to put someone to death, it must make its case to a fairly selected jury that is provided all relevant information.”

“It is now up to the government to determine whether to put the victims and Boston through a second trial, or to allow closure to this terrible tragedy by permitting a sentence of life without the possibility of release,” David Patton said in an email.

A spokesperson for the U.S. Attorney’s office in Boston said they were reviewing the opinion and had no immediate comment. Prosecutors could ask the full appeals court to hear the case or go straight to the U.S. Supreme Court.

The mother of Krystle Campbell, the 29-year-old killed in the attack, expressed outrage at the court’s decision.

“I just don’t understand it,” Patricia Campbell told  The Boston Globe. “It’s just terrible that he’s allowed to live his life. It’s unfair. He didn’t wake up one morning and decide to do what he did. He planned it out. He did a vicious, ugly thing.”

Former Massachusetts Bay Transportation Authority officer Dic Donohue, who was severely injured in a gunfight with the brothers, said the ruling was not surprising to him.

“And in any case, he won’t be getting out and hasn’t been able to harm anyone since he was captured,” he tweeted.

Tsarnaev’s lawyers acknowledged at the beginning of his trial that he and his older brother, Tamerlan Tsarnaev, set off the two bombs at the marathon finish line. But they argued that Dzhokar Tsarnaev is less culpable than his brother, who they said was the mastermind behind the attack.