The defence team, which Moussaoui has rejected, launched an assault on the US government's handling of intelligence threats before the 2001 attacks, hoping to discredit the prosecution claim that Moussaoui's "lies" allowed time for strikes to go ahead in New York and Washington.
Closing arguments are next on the agenda, with each side having one hour to speak, before Judge Leonie Brinkema issues her instructions to the jury and hands them the case.
Jurors must decide whether Moussaoui's responsibility in September 11 is strong enough to make him eligible for the death penalty. If it backs the prosecution claim a new phase of hearings will be held to decide if the 37-year-old Frenchman should be executed.
The jury was shown videotaped extracts of top US administration officials testifying to an official commission on the US government failures that the September 11 hijackers were able to exploit.
The extracts from the hearings in 2004 featured Secretary of State Condoleezza Rice, testifying while she was still national security advisor, then CIA director George Tenet and former White House anti-terrorism coordinator Richard Clarke.
The final defence evidence was a film in which Mr Clarke apologised to the families of the nearly 3,000 September 11 victims.
"Your government failed you. Those entrusted with protecting you failed you and I failed you," Mr Clarke was seen saying.
Moussaoui earlier made surprise claims that he had a leading role in the September 11 plot and had been ordered by Al-Qaeda leader Osama bin Laden to fly a fifth plane into the White House.
After the defence case ended, the prosecution came back to present a final witness, FBI agent James Fitzgerald, who told how Moussaoui offered during a February 2 meeting to testify against himself if the government made a deal.
"He said he was to pilot a fifth plane and then he declined to answer other questions," Mr Fitzgerald told the jury. "He said the government would have to agree to a deal first."
Mr Fitzgerald said Moussaoui never asked for the government to drop the death penalty demand. "He just did not wish to spend all his life in a jail in Colorado. He wanted better jail conditions."