U.S. prosecutors plan to seek the death penalty for Zacarias Moussaoui, the French-Moroccan charged with conspiring to kill and maim thousands of people in America on Sept. 11, according to government officials and a letter sent by prosecutors to victims' families.

The Justice Department has not given final approval to prosecutors to push for the death penalty for the alleged "20th hijacker," but officials have until March 29 to make a decision, according to two officials who spoke on the condition of anonymity.

In the meantime, prosecutors are preparing to argue that the man they allege trained alongside the Sept. 11 hijackers be put to death.

Moussaoui, 33, is the only person charged in the Sept. 11 terrorist attacks — the government accusing the French citizen of Moroccan descent of conspiring with Usama bin Laden, the hijackers and others to commit the attacks. His trial is scheduled to begin Sept. 30.

The government's intention to seek the death penalty in the case was first disclosed in a letter from U.S. Attorney Paul McNulty and lead prosecutor David J. Novak to at least dozens of victims' families.

The letter, dated March 7, said that if the Justice Department gave final approval, "the Moussaoui case will become a capital prosecution, meaning that the United States will be asking the jury to find that defendant Moussaoui should be executed should he be found guilty."

The letter said prosecutors would seek out 30 families to testify about how the terrorist attacks affected them. This testimony would be needed during the punishment phase of the trial, should Moussaoui be found guilty, the letter said.

"The individual stories of approximately 30 victims ... will serve as a microcosm of all," it said. "Obviously, we cannot tell the story of every victim; otherwise, the trial would last forever."

Stephen Push, whose wife, Lisa Raines, was killed when a hijacked plane hit the Pentagon, is among those who received the letter.

"The prosecutors have been extremely helpful in terms of keeping us informed and I plan to help out in anyway I can," Push, of Great Falls, Va., said Monday.

Attorney General John Ashcroft is a longtime and staunch supporter of the death penalty.

Government officials said that defense lawyers were so certain that the death penalty would be sought that they had declined to attend a Justice Department hearing during which they could have tried to persuade the government not to ask for death, according to The New York Times, which first reported on the government's intentions.

Moussaoui refused to enter a plea at his arraignment, saying: "In the name of Allah, I do not have anything to plead. I enter no plea. Thank you very much."

U.S. District Judge Leonie Brinkema then she said she took that to mean he was pleading not guilty to the charges. 

Moussaoui remained silent, but one of his lawyers, Frank Dunham, answered, "Yes." The judge then entered a not guilty plea into the court record.

In France, Moussaoui's brother said Monday that he was refusing to cooperate with a U.S. official involved in his prosecution.

The official was identified by French judicial authorities as being from federal court in Alexandria, Va., where Moussaoui was indicted. He traveled to the southern French city of Montpellier to speak to the family.

The U.S. official, whose name was not released, met with Moussaoui's brother, Abd Samad Moussaoui, a teacher at a technical high school.

The meeting took place at a local police station and afterward Moussaoui's brother told reporters that he had "refused to cooperate" with the U.S. official.

On Tuesday, the U.S. official was to question the suspect's mother, Aicha, who lives in nearby Narbonne.

The Associated Press contributed to this report.