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Federal investigators again questioned New York City subway shooting suspect Frank James this week, then took a DNA sample that his defense attorneys argue may have violated his rights.

"FBI agents entered his cell at MDC Brooklyn, questioned him, took multiple buccal swabs of his DNA, and directed him to sign certain documents," his federal defenders wrote to Judge Roanne Mann, referring to the Metropolitan Detention Center, a federal holding facility. "Contrary to standard practice the government committed this intrusion absent advance notice to counsel, depriving us of an opportunity to be heard or to be present."

The lawyers, Mia Eisner-Grynberg and Deirdre von Dornum, also alleged that the FBI violated federal criminal procedure.

Left: New York City Police, left, and law enforcement officials lead subway shooting suspect Frank R. James, 62, center, away from a police station, in New York, Wednesday, April 13, 2022. Right: Mia Eisner-Grynberg and Deirdre von Dornum, assistant federal defenders with the Federal Defenders of New York and attorneys for Frank James, speak outside Brooklyn Federal Court following James's arraignment in New York City, U.S., April 14, 2022.

Left: New York City Police, left, and law enforcement officials lead subway shooting suspect Frank R. James, 62, center, away from a police station, in New York, Wednesday, April 13, 2022. Right: Mia Eisner-Grynberg and Deirdre von Dornum, assistant federal defenders with the Federal Defenders of New York and attorneys for Frank James, speak outside Brooklyn Federal Court following James's arraignment in New York City, U.S., April 14, 2022. (AP Photo/Seth Wenig | REUTERS/Brendan McDermid)

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"Because the government failed to provide notice to counsel before questioning and searching Mr. James, their practice risked violations of Mr. James’s core constitutional rights under the Fourth, Fifth and Sixth Amendments," they wrote. "Using a swab on a person’s inner cheek in order to obtain DNA evidence is a search subject to constitutional scrutiny."

Federal prosecutors called the claim "hyperbole" and responded with a letter of their own, stating, "His DNA was obtained pursuant to a judicially authorized search warrant and no violations of any of the defendant’s constitutional rights occurred in the execution of the warrant."

They said they had a warrant for collecting James' DNA and denied any violation of his rights.

James is accused of throwing smoke grenades and opening fire on a crowded N train in Sunset Park on April 12. He allegedly shot 10 people and injured more than two dozen before sneaking off into the streets of New York. All of the victims survived.

In this image obtained by Fox News, Frank James is spotted walking.

In this image obtained by Fox News, Frank James is spotted walking on Wednesday, April 13 in Manhattan. (Jack Griffin via Twitter)

BROOKLYN SUBWAY SHOOTING SUSPECT FRANK JAMES IN CUSTODY

Police found the 62-year-old alleged gunman on April 13 after tips from the public, including an apparent call he made to Crime Stoppers himself.

"Mr. James is now facing a federal charge for his actions: A terrorist attack on mass transit," said Michael J. Driscoll, assistant director in charge of the New York Field Office of the FBI, said at a news conference following the arrest.

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NYPD Chief of Detectives James Essig said that James' arrest history includes nine prior arrests in New York from 1992 and 1998, including for criminal sex act, four instances of possession of burglary tools and two instances of theft of service. He was also arrested at least three times in New Jersey in 1991, 1992 and 2007, for trespassing, larceny and disorderly conduct.

Now he faces up to life in prison if convicted for the subway attack.