The Justice Department will seek the death penalty against Zacarias Moussaoui, the Frenchman accused of being the missing "20th hijacker" in the Sept. 11 terrorist attacks, according to federal officials and a department letter sent to families of some who died in the attacks. 

Attorney General John Ashcroft, a longtime supporter of the death penalty, has not given Moussaoui's prosecutors the official authorization to seek capital punishment, but the Justice Department has until March 29 to decide, according to two anonymous officials. 

Nevertheless, the prosecution is preparing to present a capital case against the man alleged to have trained and planned alongside the Sept. 11 hijackers. 

Moussaoui, born in France 33 years ago to Algerian immigrant parents, has been the only person charged so far in direct connection to the attacks. Four of the six counts against him carry the maximum sentence of death. His trial is scheduled to begin Sept. 30. 

The intention to seek the death penalty was first disclosed in a March 7 letter from U.S. Attorney Paul McNulty and lead prosecutor David J. Novak to the families of dozens of people killed on Sept. 11. 

If the Justice Department allowed them to, McNulty and Novak wrote, "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." 

Click here to read the letter sent to the families of the victims.

On Sept. 11, Moussaoui was in a jail cell in Minnesota, having been arrested the previous month for visa violations after personnel at the flight school where he was training became suspicious. 

The fact that only four men hijacked United Airlines Flight 93, which crashed into a Pennsylvania field during a struggle with the passengers, while teams of five men took over each of the planes that crashed into the World Trade Center towers and the Pentagon, led investigators to quickly conclude that a missing "20th hijacker" must have been prevented from carrying out his mission. 

Further interrogation of Moussaoui, as well as an examination of his computer, which revealed information that might have tipped off authorities about the imminent attacks, led the FBI to believe that Moussaoui was slated to have joined in the hijackings. 

The circumstantial evidence against Moussaoui is overwhelming, but although his movements, interests, purchases and acquaintances mirror those of some of the 19 hijackers, investigators are still looking for a "smoking gun" that would tie Moussaoui directly to any of them. 

McNulty and Novak's letter said prosecutors would ask 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 American Airlines Flight 77 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. 

Asked whether Moussaoui should get the death penalty, Push hesitated and then said, "That is not for me to say. That is for the judge and the jury to determine." 

Government officials said 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 in Tuesday's editions. 

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

Moussaoui's mother, Aicha Moussaoui, skipped a Tuesday appointment for questioning by the same official, police said. 

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

The government of France has indicated that it would oppose a death sentence if Moussaoui were convicted. 

The Associated Press contributed to this report.