In a surprise development for the on-again, off-again military commissions at Guantánamo Bay, Cuba, the Pentagon's chief war crimes prosecutor has abruptly resigned in a dispute over his independence.

Air Force Col. Morris Davis was known in some circles for his colorful descriptions of the alleged war criminals held at the remote U.S. Navy base in Cuba, at one point likening detainees challenging the trial system to vampires afraid of the harsh sunlight of American justice.

''Remember if you dragged Dracula out into the sunlight, he melted? Well, that's kind of the way it is trying to drag a detainee into the courtroom,'' Davis told reporters taken to Guantánamo to cover trials in March 2006. ``But their day is coming. . . . The defense has tried to hide. They're going to show up in the courtroom.''

Then, suddenly, Davis stepped down on Thursday in a dispute over whether Air Force Brig. Gen. Thomas Hartmann, legal advisor to the administrator overseeing the trials, has the power to supervise aspects of the prosecution.

A panel of three military lawyers studied the command structure of the Office of Military Commissions, said Bryan Whitman, a Pentagon spokesman, and Davis was informed Thursday that Hartmann did have access to ``attorneys, documents and other relevant information in the office of the chief prosecutor.''

The Wall Street Journal first reported the resignation Friday morning.

Whitman noted that Davis, a career Air Force officer, had not resigned his U.S. military commission but had asked for ''reassignment'' to another job elsewhere in the Defense Department.

Whitman said the loss of the chief prosecutor should not stall current plans to stage an arraignment in November of the lone current candidate for a war crimes trial -- long-held Canadian captive Omar Khadr, 21, accused of the July 2002 grenade killing of a U.S. Army Special Forces medic in Afghanistan.

''The Office of Military Commissions isn't built around any one lawyer or any one prosecutor,'' Whitman said. ``I don't anticipate that this development would have any impact on our ability to move forward.''

Davis was the second prosecutor to lead the beleaguered commissions system, which the Pentagon designed in the aftermath of the 9/11 attacks to try select war-on-terror captives outside traditional U.S. military or civilian courts.

No full-blown trial has been held, in large part because the commissions have been shut down once by the federal courts, ruled unconstitutional by the U.S. Supreme Court and reauthorized by Congress,

Davis had said he hoped to prosecute as many as 80 of the detainees at Guantánamo, which today number about 330, among them so-called ''high-value'' once CIA-held captive Khalid Sheik Mohammed, alleged mastermind of the 9/11 attacks.

Friday, Davis declined to speak to The Miami Herald, saying he was forbidden to talk to the media under an order issued by both Hartmann and the general's boss, the so-called convening authority for military commissions, Susan Crawford.

No replacement had been chosen Friday, Whitman said.

And it was not immediately clear whether a deputy prosecutor, a retired colonel and civilian named Francis Gilligan, had assumed the responsibilities of running an office of uniformed American military lawyers seeking to stage the first U.S. war crimes tribunals since World War II.

The tribunal structure is intended to put on trial captives who the Bush administration says do not meet the definition of prisoners of war and therefore are terrorists.

As legal advisor, Hartmann has a sweeping supervisory role in the trials -- from running an office that reviewed charges to help plan an expeditionary-style $10 million tent city being built to stage them.

Hartmann's predecessor, Air Force Col. Thomas Hemingway, was also directly involved in arranging the lone conviction under the process -- a March plea agreement by Australian captive and former al Qaeda trainee David Hicks that allowed him to serve out his sentence in his homeland and be released on New Year's Eve.