Prosecutors on Tuesday unveiled federal murder charges against the man charged with opening fire on members of the National Guard in Washington last year, raising the possibility that the government could seek the death penalty if he is convicted.

Rahmanullah Lakanwal pleaded not guilty to similar charges last year and pleaded not guilty to the new charges handed up by a federal grand jury on Tuesday, which prosecutors read aloud during a hearing in Federal District Court in Washington. Under an earlier indictment, he had been charged with first degree murder as a violation of D.C. law. But the city abolished the death penalty in 1981, making the penalty unavailable had Mr. Lakanwal been convicted.

During a hearing before Judge Amit P. Mehta, a government lawyer said the Justice Department had started the process of determining whether to seek the death penalty, which involves reviewing evidence and consulting with the U.S. attorney’s office.

The lawyer added that it was “impossible to say” how long it could take the government to reach a determination. But he drew parallels to the case against Elias Rodriguez, the man accused of killing two Israeli embassy staff members last year. Jeanine Pirro, the U.S. attorney in Washington, indicated in May that her office would pursue the death penalty in that case, nearly a year after Mr. Rodriguez was arrested.

Mr. Lakanwal, an Afghan national who aided U.S. forces during the war in his country as part of a C.I.A.-backed paramilitary unit, entered the United States in 2021 under an asylum program set up during the Biden administration.

He is charged with the murder of Sarah Beckstrom, a specialist in the National Guard who was stationed in Washington last year after President Trump brought hundreds of Guard members from various states to patrol the capital. Mr. Lakanwal was also charged with shooting and attempting to murder Air Force Staff Sgt. Andrew Wolfe, and with attempting to kill two other Guard members referred to only by their initials, who subdued him after the shooting.

Ms. Beckstrom and Mr. Wolfe were deployed from the West Virginia National Guard as part of the law enforcement surge Mr. Trump launched last August.

Prosecutors said they had collected “hundreds of hours” of video from body cameras and surveillance cameras that they were reviewing as part of the case.

Judge Mehta ordered the parties to reconvene on Sept. 16. Mr. Lakanwal appeared in court in a wheelchair and an orange jumpsuit, and listened to the hearings through a Pashto interpreter.