In a stunning turnaround, the former chief military prosecutor at Guantanamo Bay said Thursday he would be a defense witness for the driver of Osama bin Laden.

Air Force Col. Morris Davis, who resigned in October over alleged political interference in the U.S. military tribunals, told The Associated Press he will appear at a hearing for Salim Ahmed Hamdan.

"I expect to be called as a witness ... I'm more than happy to testify," Davis said in a telephone interview from Washington. He called it "an opportunity to tell the truth."

At the April pretrial hearing inside the U.S. military base in southeast Cuba, Hamdan's defense team plans to argue that alleged political interference cited by Davis violates the Military Commissions Act, Hamdan's military lawyer, Navy Lt. Brian Mizer, told the AP.