A few days before testimony begins, lawyers for Dzhokhar Tsarnaev have again asked a federal judge to dismiss the case, saying the court failed to summon a diverse cross-section of residents for jury service, in violation of Tsarnaev’s right to a fair trial.

US District Court Judge George A. O’Toole Jr. already rejected a request to dismiss the indictment on similar grounds — the defense had previously argued that the court’s process of summoning jurors for grand jury service from a "jury wheel" was faulty. The jury wheel is a list of people who are eligible for jury duty.

Tsarnaev’s latest motion, filed Thursday morning, reiterated those concerns related to the quality of the jury that will ultimately determine Tsarnaev’s fate. While acknowledging that O’Toole has already rejected their arguments, the request is part of a strategy to preserve Tsarnaev’s appellate rights — meaning that filing the motion allows them to later raise the issue with a federal appeals court if Tsarnaev is convicted.

Thursday’s request also went further and raised concerns with the handling of the final pool for the trial jury. The lawyers said the reassignment of juror numbers, based on when potential jurors arrived at the courthouse, interfered with the randomness of the jury selection process and the jury pool’s diversity.

”This reordering, apparently based on nonrandom factors such as arrival time, had systemic effects on the order," the lawyers argued. "The reordering was not random and had nonneutral effects on cognizable groups."

The lawyers said the renumbering decreased the number of potential jurors who were African-American, increased the number who were white, decreased the number of Boston residents, and decreased the number of those younger than 30.

A defense consultant, for example, compared the reordering of the jurors to the original ordering and found that there would have been five potential black jurors among the first 94 in the original order, compared with zero in the new order.

The lawyers also took issue with a local court rule that allows jurors age 70 or older to refuse jury service, saying 95.96 percent of that group called for service in Tsarnaev’s trial chose not to serve. Meanwhile, that demographic makes up 14.60 percent of the population, resulting in an "absolute disparity" and "under representation" of persons over 70.

”The Sixth Amendment secures to criminal defendants the right to be tried by an impartial jury drawn from sources reflecting a fair cross section of the community," Tsarnaev’s lawyers argued. "Extra precautions must be taken to protect the defendant’s right to an impartial and representative jury in a capital case because of the broad discretion given the jury at the death-penalty hearing and the special seriousness of the risk of improper sentencing."

Tsarnaev, 21, faces multiple charges that carry the possibility of the death penalty. He is accused of helping to plant the bombs at the Marathon finish line the afternoon of April 15, 2013, that killed Martin Richard, Krystle Marie Campbell, and Lingzi Lu, and injured more than 260 others.

Tsarnaev and his older brother and alleged accomplice, Tamerlan Tsarnaev, also allegedly shot and killed Massachusetts Institute of Technology police Officer Sean Collier before attempting to flee the area.

Tamerlan Tsarnaev was killed in a confrontation with police. Dzhokhar Tsarnaev was arrested after he was found hiding in a dry-docked boat in Watertown.

On Wednesday, the court said more than 64 suitable people have been identified who could serve on a "death-qualified" jury. The selection process, which began Jan. 5, is now slated to be completed Tuesday when a final jury of 12 and six alternates is expected to be seated.

By Wednesday, the judge will swear in the jury before opening statements are heard.

A federal appeals court has been considering a defense request to intervene and force O’Toole to move the trial but has not yet ruled. O’Toole has continued moving forward with the case.

© 2015 The New York Times Company