From CNN.com:
(CNN) -- A former top aide to Colin Powell says his involvement in the former secretary of state's presentation to the United Nations on Iraq's weapons of mass destruction was "the lowest point" in his life.

"I wish I had not been involved in it," says Col. Lawrence Wilkerson, a longtime Powell adviser who served as his chief of staff from 2002 through 2005. "I look back on it, and I still say it was the lowest point in my life."

Wilkerson is one of several insiders interviewed for the CNN Presents documentary "Dead Wrong -- Inside an Intelligence Meltdown." The program, which aired Sunday, pieces together the events leading up to the mistaken WMD intelligence that was presented to the public. A presidential commission that investigated the pre-war WMD intelligence found much of it to be "dead wrong."

Powell's speech, delivered on February 5, 2003, made the case for the war by presenting U.S. intelligence that purported to prove that Saddam Hussein had weapons of mass destruction. Wilkerson says the information in Powell's presentation initially came from a document he described as "sort of a Chinese menu" that was provided by the White House.

"(Powell) came through the door ... and he had in his hands a sheaf of papers, and he said, 'This is what I've got to present at the United Nations according to the White House, and you need to look at it,'" Wilkerson says in the program. "It was anything but an intelligence document. It was, as some people characterized it later, sort of a Chinese menu from which you could pick and choose."

Wilkerson and Powell spent four days and nights in a CIA conference room with then-Director George Tenet and other top officials trying to ensure the accuracy of the presentation, Wilkerson says.

"There was no way the Secretary of State was going to read off a script about serious matters of intelligence that could lead to war when the script was basically un-sourced," Wilkerson says.

In one dramatic accusation in his speech, Powell showed slides alleging that Saddam had bioweapons labs mounted on trucks that would be almost impossible to find.

"In fact, Secretary Powell was not told that one of the sources he was given as a source of this information had indeed been flagged by the Defense Intelligence Agency as a liar, a fabricator," says David Kay, who served as the CIA's chief weapons inspector in Iraq after the fall of Saddam. That source, an Iraqi defector who had never been debriefed by the CIA, was known within the intelligence community as "Curveball."

After searching Iraq for several months across the summer of 2003, Kay began e-mailing Tenet to tell him the WMD evidence was falling apart. At one point, Wilkerson says, Tenet called Powell to tell him the claims about mobile bioweapons labs were apparently not true.

"George actually did call the Secretary, and said, 'I'm really sorry to have to tell you. We don't believe there were any mobile labs for making biological weapons,'" Wilkerson says in the documentary. "This was the third or fourth telephone call. And I think it's fair to say the Secretary and Mr. Tenet, at that point, ceased being close. I mean, you can be sincere and you can be honest and you can believe what you're telling the Secretary. But three or four times on substantive issues like that? It's difficult to maintain any warm feelings."