It was U.S. Secretary of State Colin Powell’s Feb. 5, 2003 address to the United Nations which convinced Bob Drogin that Saddam Hussein had stockpiles of weapons of mass destruction.

Until then, said Mr. Drogin, who covers issues of weapons proliferation, terrorism and intelligence — nukes, kooks and spooks — out of Washington for the Los Angeles Times, “I was a sceptic.”

He had been following the Bush administration’s attempts to make a case for war, and knew there were holes in it. But Mr. Powell’s detailed presentation, the center-point of which was allegations about Saddam’s mobile biological weapons production facilities, won him over.

He did not stay convinced for long, though.

“Shortly after the invasion I went to Baghdad and spent a month or so with the people sent out to find the WMD,” he said last week. “When I came back I was fairly convinced this whole thing was a fraud. I was frustrated and disillusioned and angry.”

So he set out to find how “we as a nation had been so bamboozled.”

The result of that investigation is his award-winning book, Curveball: Spies, Lies and the Con Man Who Caused a War, much of which was written here, at his West Tisbury home.

There is perhaps a little poetic licence in that title, for clearly no single individual or event caused the Iraq war. But what the book makes crystal clear is that Ahmed Hassan Mohammed, the Iraqi defector code-named Curveball, did more than any other single individual to give the Bush administration hawks the pretext they needed to invade.

What the book documents is something akin to chaos theory — you know, a butterfly flaps its wings in the Brazilian rainforest and ends up creating a hurricane — only applied to politics and intelligence.

In this case, an Iraqi refugee went to Germany in 1999 began to spin a story about mobile biological weapons labs run by Saddam.

“His goal was not to start a war or overthrow Saddam,” said Mr. Drogin. “He was just trying to get a visa. And he was a con man, a crook and a fraud and a liar.”

“His information was spun up through a system that operates like a children’s game of telephone, where the information became steadily more changed in its character and degree of fear until by the beginning of 2003, President Bush is citing his information in the State of the Union speech, and most importantly, Colin Powell, the Secretary of State, uses it as the high point of his address to the [United Nations] Security Council, in appealing for support to go to war.”

“What he [Powell] didn’t know at the time was that not only had the CIA never interviewed this informant, they didn’t even know his name. He was still under the control of the German intelligence service. His information had never been confirmed. His background had never been vetted.

“And yet because it confirmed what intelligence already believed, it was taken as gospel.”

“Curveball is the defining story of what I think is the greatest intelligence failure in our history,” Mr. Drogin said.

That’s a big call, but not unreasonable in light of the facts.

As Mr. Drogin summarizes: there were three parts to the WMD argument, nuclear, chemical and biological.

Even before the war, the nuclear argument had been debunked. Mohamed el Baradei, head of the International Atomic Energy Agency, told the Security Council there was nothing there. Furthermore, the documents the U.S. had given the IAEA, about alleged Iraqi importation of uranium from Niger, were forgeries.

“And after the war we discovered the CIA analysts who seemed so cocksure about Saddam’s chemical weapons in fact thought the evidence very ambiguous, until they saw the judgments coming in from the analysts on biological weapons. They thought ‘biological are harder to make than chemical, so if they’re sure he’s got bio, he must have chemical’.

“So they ramped up.

“And all of the bio stuff came from Curveball.”

It was in March 2004, a year after the invasion, when Mr. Drogin first learned of Curveball.

A close contact of his, David Kay, the head of the Iraq Survey Group — the group sent to find the non-existent WMD — had returned to the States and was pushing for a public admission it had all been a terrible mistake.

Mr. Kay’s message was not well-received by an administration even then trying to spin the WMD story as best they could.

Said Mr. Drogin: “When David was hired for job, he was given an office at the CIA, on the seventh floor, just down the hall from George Tenet. He had an executive parking spot, and had the run of the place.

“When he came back his office was in another wing, at the end of a hallway filled with construction material. He didn’t have a working computer, he wasn’t invited to meetings, he lost the executive parking space. He was treated like Typhoid Mary.

“So he quit. Then he was invited to testify before the Senate ... and famously said ‘we were all wrong’.”

Well, Mr. Tenet was furious, and responded with his own speech on Feb. 5, exactly one year after Mr. Powell’s UN presentation. Mr. Drogin attended.

“One of the things he said that day was that they had still not spoken to the chief source of the intelligence on biological weapons,” he recalled.

“It hit me like a two-by-four across the head, because I remembered so clearly those drawings Colin Powell had shown us a year to the day before.”

And six weeks later, on March 20, he broke the first story on Curveball.

Mr. Drogin was uniquely positioned to write it. He had asked to cover the intelligence beat — which was not a hot one before September 2001 — after he returned to Washington in 1998, following some 10 years as a foreign correspondent.

“In the post cold war period people weren’t paying much attention, so it was a good time to get to know people,” he said.

That was in the days when the LA Times had yet to be afflicted by its recent severe staff cuts, so he was given the time and space to pursue the truth of the administration’s claims.

And, when the balloon went up on the intelligence failures leading up to war, he already had the contacts.

“I really felt I knew that story better than anyone. I knew how intelligence works, I had access to CIA people. The Germans had agreed to co-operate — that’s unusual — so did the British. I’d been to Iraq, I knew a lot of the weapons inspectors.

“And this was a story that just fascinated me.

“Politics aside, it showed how well-meaning people, patriotic, smart people can be so blinded by their own fears of what might be out there. So, they conjured up this terrifying weapons system, that had never existed.”

He spent 2006 writing the book, a lot of it here on the Island in his West Tisbury home; his mother is a longtime summer resident of Edgartown. After editing, it came out October last year. It has since won two awards, the Cornelius Ryan Award from the Overseas Press Club for the best non-fiction book on international affairs for 2007, and the Investigative Reporters and Editors’ best investigative book.

It’s been translated into eight languages, and film rights have been sold, although Mr. Drogin said the actual production of a movie is being hampered by the fact that “every movie on Iraq to date has tanked.”

And Mr. Drogin is now working to revise it; since the book came out, Curveball himself has spoken.

“This guy was just a nobody, a nothing. Since the book came out we’ve talked to him, and he can’t hold a job, he’s bouncing around from McDonald’s to Burger King to a pretzel shop. He keeps getting fired for lying and just being a crackpot.”

Not a bad result, for a first book.

Mr. Drogin would like to write another, but concedes there was something special about the circumstances which led him to this one, which will probably never be repeated.

“As a kid I grew up loving spy stories and westerns and this is like the perfect blend of the two,” he said.

The spy part is easy to see — the false information, the intra-agency conflict, the international suspicion and rivalries. But how is it like a wester?

“This is just a classic story of a stranger comes to town and all hell breaks loose,” he said.

And a footnote. Mr. Drogin was going to end his international promotional tour for the book with an appearance at the Bunch of Grapes.

Obviously that did not happen, but when he strolled down Main street, Vineyard Haven after the fire, and looked in the bookstore window, there was Curveball, still there, albeit a bit singed.