BOSTON (AP) — A federal appeals court on Thursday ordered Boston Marathon bomber Dzhokhar Tsarnaev's case to be returned to a lower court to probe claims of juror bias and determine whether his death sentence should stand.

The ruling from the Boston-based 1st U.S. Circuit Court of Appeals keeps intact Tsarnaev's death sentence for now. But the judge's found that further investigation is needed to determine whether two jurors should have been stricken for biases.

If the lower court's investigation reveals either person should have been disqualified, the court should vacate Tsarnaev's death sentence and hold a new penalty-phase trial to determine whether he should sentenced to death, the court said.

"And even then, we once again emphasize that the only question in any such proceeding will be whether Tsarnaev will face execution; regardless of the outcome, he will spend the rest of his life in prison," the court said.

The Boston-based appeals court issued its ruling more than two years after the U.S. Supreme Court reinstated the sentence imposed on 30-year-old Tsarnaev for his role in the bombing that killed three people and injured hundreds near the marathon's finish line in 2013.

The 1st Circuit took another look at the case after Tsarnaev's lawyers urged it to examine issues the Supreme Court didn't consider. Among them was whether the trial judge wrongly forced the trial to be held in Boston and wrongly denied defense challenges to seating two jurors they say lied during questioning.

The appeals court first overturned Tsarnaev’s death sentence in 2020 and ordered a new penalty-phase trial to decide whether he should be executed. The court found then that the trial judge did not sufficiently question jurors about their exposure to extensive news coverage of the bombing. The Supreme Court justices voted 6-3 in 2022 when they ruled that the 1st Circuit’s decision was wrong.

Despite a moratorium on federal executions imposed by Attorney General Merrick Garland, the Justice Department has continued to push to uphold the death sentence in Tsarnaev’s case. The moratorium came after former President Donald Trump administration’s put to death 13 inmates in its final six months.

Oral arguments before the three-judge 1st Circuit panel more than a year ago focused on two jurors Tsarnaev’s lawyers say were dishonest during the lengthy jury selection process.

One of them said she had not commented about the case online, while Tsarnaev’s attorneys say she had retweeted a post calling Tsarnaev a “piece of garbage.” Another juror said none of his Facebook friends had commented on the trial, even though one had urged him to “play the part” so he could get on the jury and send Tsarnaev to “jail where he will be taken of,” defense attorneys say. Tsarnaev’s lawyers raised those concerns during jury selection, but say the judge chose not to look into them further.

William Glaser, a Justice Department lawyer, acknowledged during oral arguments before the 1st Circuit appeals court that the jurors made inaccurate statements, but said other disclosures suggested they misremembered rather than lied. He argued that the trial judge did nothing wrong.

Tsarnaev’s guilt in the deaths of Lingzi Lu, a 23-year-old Boston University graduate student from China; Krystle Campbell, a 29-year-old restaurant manager from Medford, Massachusetts; and 8-year-old Martin Richard, of Boston, was not at issue in the appeal, only whether he should be put to death or imprisoned for life.

Defense lawyers argued that Tsarnaev had fallen under the influence of his older brother, Tamerlan, who died in a gun battle with police a few days after the April 15, 2013, bombing.

Tsarnaev was convicted of all 30 charges against him, including conspiracy and use of a weapon of mass destruction and the killing of Massachusetts Institute of Technology Police Officer Sean Collier during the Tsarnaev brothers’ getaway attempt.

Prosecutors told jurors that the men carried out the attack to punish the United States for its wars in Muslim countries. In the boat where Tsarnaev was found hiding, he had scrawled a confession that referred to the wars and wrote, among other things, “Stop killing our innocent people and we will stop.”