Last week, a jury in Guantanamo Bay convicted Salim Hamdan of a war crime. But according to a new book, the government might have turned down an opportunity to turn Hamdan into a friendly source.

Jonathan Mahler writes in <i>The Challenge</i> that Hamdan's FBI interrogator warned against a Gitmo trial for the former bin Laden chauffeur. (Credit: Neal Katyal/Reuters/Handout) In The Challenge, New York Times Magazine writer Jonathan Mahler reports that one of the FBI's top agents believed Hamdan was ready to provide key evidence against top level al-Qaida players. The government's best shot at getting the info, the agent argued, would be to offer Hamdan a plea deal in federal court. Instead, the administration sent Hamdan to the U.S.'s first war crimes tribunal in 60 years, which ended in a less-than-complete victory for the government.

Mahler reports that FBI agent Ali Soufan -- one of the few FBI agents who spoke Arabic -- had interrogated Hamdan at Guantanamo Bay and found he had lots of potentially useful information. While Hamdan was only a bit player, he was a valuable witness. For example, Hamdan had apparently witnessed Khalid Sheikh Mohammed debrief Osama bin Laden on the 9/11 operation.

Instead of prosecuting Hamdan, Mahler writes, Soufan thought he "could persuade Hamdan to plead guilty and cooperate with the government in exchange for a lighter sentence." After all, Soufan argued, if the government moved ahead with a tribunal, Hamdan would eventually get a lawyer and clam up.

The administration, of course, declined to take Soufan's advice and opted for a tribunal.

"Soufan's access to Hamdan was immediately cut off," writes Mahler, "and the FBI lost a crucial source of information, as well as a potential key witness in other al-Qaida trials."

We've excerpted the relevant passage (PDF). (Also, as a bit of a bonus, we've posted the book's prologue.)

We spoke briefly with Mahler about the incident.