Prosecutors will not appeal the Boston Marathon bombing ruling, paving the way for a hearing on possible jury bias.

Federal prosecutors will not challenge an appeals court ruling in the death penalty case against Boston Marathon bomber Dzhokhar Tsarnaev. The ruling requires the judge who presided over his 2015 trial to delve into the defense’s claims that two jurors were biased and should have been excused during jury selection.

In a one-page letter Wednesday, the Justice Department told the U.S. First Circuit Court of Appeals that it was not seeking a hearing before all 10 judges on the court, or a rehearing before the panel of three judges threw the case back. for further investigation to the lower court. It is unclear whether Tsarnaev will be returned to the federal courthouse in Boston to watch proceedings over possible juror bias. The court has not yet set dates.

The 30-year-old Tsarnaev, who along with his brother detonated bombs near the finish line of the marathon in 2013 that killed three people and injured 260 others, is currently on death row in a federal supermax prison in Colorado. He admitted at his trial that he planted a bomb in a backpack outside the Forum restaurant on Boylston Street, killing 8-year-old Martin Richard and Lingzi Lu, a 23-year-old Boston University graduate student from China. Tsarnaev was also found responsible for the murder of MIT police officer Sean Collier days after the explosion while he and his brother were on the run.

Evidence showed that his older brother, Tamerlan Tsarnaev, planted the bomb that killed 29-year-old Krystle Campbell of Arlington. Tamerlan Tsarnaev, 26, later died during a shootout with police in Watertown. His lawyers opposed the death penalty, saying the then 19-year-old was influenced by his brother and therefore less responsible. But jurors concluded he showed no remorse for his actions and should be sentenced to death for his role in the killings.

Two years ago, the U.S. Supreme Court reinstated Tsarnaev’s death sentence, ruling that the appeals court erred when it overturned that sentence on the grounds that he did not receive a fair trial. Then in March, the U.S. First Circuit Court of Appeals ruled 2-1 that the judge, U.S. District Judge George A. O’Toole Jr., erred in rejecting a defense request to excuse two jurors during jury selection without pointing out the claims that they lied about social media posts.

One juror said she had not commented on the case, but the defense found her had tweeted or retweeted 22 times about the bombings, including a retweet calling Tsarnaev a “piece of trash,” the court documents said. Another juror said none of his Facebook friends had commented on the trial, yet a friend had urged him to “play the part” so he could get on the jury and send Tsarnaev “to prison where he would be cared for’.

The appeals court ruled that O’Toole’s investigation into defense claims about possible juror bias “fell short of what was constitutionally required” and remanded the case back to the judge for further consideration.

“If and only if the district court’s investigation shows that either juror should have been punished for bias, Tsarnaev is entitled to a new sentencing phase,” the appeals court wrote.

Shelley Murphy can be reached at [email protected]. follow her @shelleymurph.