"He was between two worlds, sometimes cooperative, sometimes aggressive," said the BND supervisor. "He was not an easy-going guy."
"He knew he was important," said the BND analyst. "He was not an idiot."
Defectors are often problem sources. Viewed as traitors back home, many embellish their stories to gain favor with spy services. In the shadow world of intelligence, Curveball's inability or reluctance to provide many details actually helped convince analysts he was telling the truth.
Had Curveball claimed expertise with biological weapons or direct access to other secret programs, said the BND analyst, "It would be easier to assume he was lying."
A former British official involved with the case said Curveball's behavior should be seen through another lens. He is convinced that Curveball was under intense stress, terrified both that his visa scam would be exposed, and that his lies would be used to start a war.
"He must have been scared out of his mind," he said.
But concerns about Curveball's reliability were growing. In early 2001, the CIA's Berlin station chief sent a message to headquarters noting that a BND official had complained that the Iraqi was "out of control," and couldn't be located, Senate investigators found.
MI6 cabled the CIA that British intelligence "is not convinced that Curveball is a wholly reliable source" and that "elements of [his] behavior strike us as typical of ... fabricators,'' the presidential commission reported.
British intelligence also warned that spy satellite images taken in 1997 when Curveball claimed to be working at Djerf al Nadaf conflicted with his descriptions. The photos showed a wall around most of the main warehouse, clearly blocking trucks from getting in or out.
U.S. and German officials feared that Ahmad Chalabi had coached Curveball after the defector said his brother had worked as a bodyguard for the controversial Iraqi exile leader. But they found no evidence.
Curveball "had very little contact with his [bodyguard] brother," the BND supervisor said. "They are not close.''
More problematic were the three sources the CIA said had corroborated Curveball's story. Two had ties to Chalabi. All three turned out to be frauds.
The most important, a former major in the Iraqi intelligence service, was deemed a liar by the CIA and DIA. In May 2002, a fabricator warning was posted in U.S. intelligence databases.
Powell said he was never warned, during three days of intense briefings at CIA headquarters before his U.N. speech, that he was using material that both the DIA and CIA had determined was false. "As you can imagine, I was not pleased," Powell said. "What really made me not pleased was they had put out a burn notice on this guy, and people who were even present at my briefings knew it."
But BND officials said their U.S. colleagues repeatedly assured them Curveball's story had been corroborated.
"They kept on telling us there were three or four sources," said the senior German intelligence official. "They said it many times."
Behind the scenes, the CIA stepped up pressure to interview Curveball. The BND finally accepted a compromise in the fall of 2002. They let CIA analysts send questions, but they could not interview the Iraqi.
The frustration was intense at the CIA. But it wasn't surprising.