BUFFALO, N.Y. — Attorneys for the white supremacist gunman who killed 10 Black people at a Buffalo supermarket told a judge Thursday that the federal charges against him should be dropped because there weren’t enough Black people and other minority groups on the grand jury that indicted him.

Payton Gendron did not attend the hearing, during which his lawyers argued that his constitutional rights to a grand jury drawn from a cross section of the community were violated.

At the hearing’s start, U.S. District Judge Lawrence Vilardo noted Gendron’s objection to the prevalence of white people on the panel seemed “a little incongruous” in the hate crimes case. He did not immediately rule on the motion.

Gendron could face the death penalty if convicted in the 2022 mass shooting at a Tops supermarket, which he targeted because of its location in a primarily Black neighborhood. Those killed ranged in age from 32 to 86. Three others were wounded.

Gendron already is serving a sentence of life in prison without the possibility of parole after pleading guilty in November 2022 to multiple state charges, including murder.

A trial on the pending federal hate crime and weapons counts is expected to begin next year. The Justice Department said it would seek the death penalty if Gendron is found guilty.

Attorney John Elmore, who represents some of the victims’ relatives in lawsuits, said Gendron’s lawyers are doing what they can to keep him alive. He said challenges to the makeup of juries rarely succeed, even though he regularly sees juries lacking minorities.

“It is very ironic that attention to this problem is being brought out in this case, where Payton Gendron committed a racially motivated homicide,” he said by phone after the hearing. “But this has been a persistent problem in our courts that needs to be addressed.”

Gendron’s lawyers argued in a court filing that Black and Hispanic people and men are “systemically and significantly underrepresented” in the lists from which jurors are selected in the Buffalo area.

“To illustrate this point, the grand jury that indicted Payton Gendron was drawn from a pool from which approximately one third of the Black persons expected and one third of the Hispanic/Latino persons expected,” Gendron’s lawyers wrote. Exacerbating the problem, they said, was that the data sources used by a vendor to pull the lists together weren’t preserved.

“We don’t know what the vendor did,” Assistant Public Defender Sonya Zoghlin said. “More importantly, the vendor doesn’t know what he did.”

Statistically, the addition of two more Black people on the 60-person grand jury panel would have balanced the panel, Vilardo said.

“Can’t that be the result of an accident,” the judge asked, rather than systemic exclusion?