THEY filed into court three weeks ago — the grieving families, the press, the curious public, the jury — expecting to see the Bush Administration lay out in devastating detail why Zacarias Moussaoui, the only person convicted in the US for his connection to the September 11, 2001, terrorist attacks, should be put to death.

What they have witnessed is a dark tragicomedy, a courtroom farce with the FBI and the Government revealed in excruciating detail as the Keystone Kops, and Moussaoui himself, hood-eyed, thickly bearded and constantly ranting, an onlooker as blunder has followed blunder.

Displaying an exceptional level of incompetence, prosecutors have managed to put the Government in the dock on charges of criminal ineptitude and cronyism, while the self-confessed al-Qaeda terrorist and disciple of Osama bin Laden they are desperate to execute sits on the sidelines, with every chance of reaching old age.

Moussaoui, 37, a Frenchman of Moroccan descent, attended flight-training school in Minnesota in early 2001. After arousing suspicion in August of that year for trying to learn how to fly a Boeing 747, he was arrested by the FBI and held on immigration charges.

In custody on September 11, 2001, he has confessed that he was training to become a pilot for a later attack on the White House, but has always denied prior knowledge of the attacks on New York and Washington. He pleaded guilty last year to conspiracy charges.

The Administration argues that he should be executed because if he had told investigators the truth after he was arrested, the FBI would have had enough information to stop the September 11 attacks. The jury is being asked to decide whether he should be executed or spend life in prison.

Enter Carla Martin, a government lawyer. The crux of the prosecution case rested on the testimony of seven aviation officials, who were going to testify that a timely confession by Moussaoui would have prevented the hijackings. In violation of the judge’s order, Ms Martin, an aviation lawyer with no prosecution experience, allowed the seven witnesses to see trial transcripts, coached them on what to say, and told one not to respond to a subpoena issued by the defence.

One witness was so irritated by her persistent e-mails that he showed them to prosecutors. They were compelled to inform Leonie Brinkema, the presiding judge.

“I’ve never seen a more egregious violation of the rule about witnesses,” she said. She threatened to dismiss the case, which would have precluded execution. Instead, she allowed two “untainted” aviation witnesses to try to bolster a significantly weakened government case.

“I felt like my heart had been ripped out,” Rosemary Dillard, whose husband, Eddie, 54, died in the Pentagon attack, said. “I felt like my Government let me down one more time.”

This week a wealth of new evidence of how the FBI bungled the Moussaoui investigation became so Pythonesque in its absurdity that even the victims’ families were roaring with laughter.

Into the witness box stepped Harry Samit, the FBI agent who arrested Moussaoui. He was called by the prosecution but became the star witness of the defence.

He said that he warned his supervisors more than 70 times that Moussaoui was an al-Qaeda operative who might be plotting to hijack an airplane and fly it into a building. He said that he was regularly thwarted by two superiors, David Frasca and Michael Maltbie, from obtaining a warrant to search Moussaoui’s flat. He accused the men of being criminally negligent.

Mr Maltbie told him that getting a warrant, which could be troublesome, might harm his — Maltbie’s — career prospects. Mr Maltbie has since been promoted.

On Tuesday Ed MacMahon, Moussaoui’s defence laywer, cross-examined Michael Rolince, of the FBI. He was there to defend the bureau, but his answers brought down the house.

Mr Rolince was forced to concede that he had never seen an April 2001 intelligence briefing paper warning that bin Laden was preparing to mount an attack, even though he had signed it. Mr MacMahon then introduced an April 13, 2001, FBI communication, approved by Mr Rolince, giving warning about bin Laden’s threat inside the US. Mr Rolince said that he had not approved it.

“Is it possible for a document to say you approved it if you have not approved it?” the judge asked.

“Absolutely,” he replied. With that, the jury, the press benches, the victims’ families and the press gallery erupted in laughter.

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