Washington ? In a federal courtroom in Alexandria, Va., the sights and sounds of a national trauma are about to go on display as never before.

Prosecutors seeking the execution of Zacarias Moussaoui will relive the full horror of Sept. 11, 2001, for the jury. They will play tapes of desperate 911 calls from inside the World Trade Center, along with the cockpit voice recorder documenting the struggle of passengers to take over hijacked United Airlines Flight 93 before it crashed in Pennsylvania.

And the government plans to call as many as 40 family members and survivors to tell their stories of loss. It is the culmination of a four-year effort by the prosecution to knit together a portrait of terror far beyond a normal death penalty trial, and it includes an unprecedented effort to reach out to the victims of Sept.11.

Some wonder if it will be too much for the jury – and the victims themselves – to bear. “I think these people testifying will be unsatisfied and many will just end up reliving the trauma,” said Richard Moran, a sociology and criminology professor at Mount Holyoke College who has testified in more than two dozen death penalty hearings.

But as Moussaoui’s sentencing trial moves into its final phase Thursday, family members and victim advocates said they welcome the decision to lay bare the most intimate details of the hijackings that killed nearly 3,000 people. “It’s important to replicate the horrors of 9/11 so the jury can make a fair and informed decision,” said D. Hamilton Peterson. His father, Donald Peterson, and stepmother, Jean Peterson, perished on Flight 93 when it crashed in a Pennsylvania field.

Moussaoui, 37, the only person convicted in the United States in connection with Sept.11, was found eligible for the death penalty Monday. Jurors will now consider whether he should be executed. They will weigh a list of aggravating factors submitted by prosecutors – ranging from Moussaoui’s lack of remorse to the destruction the attacks caused in New York – against mitigating factors that include Moussaoui’s troubled mental state.