Janet Hamlin, Associated Press
The five Sept. 11, 2001 attack co-defendants sit during a hearing at the U.S. Military Commissions court for war crimes, at the U.S. Naval Base, in Guantanamo Bay, Cuba. From top to bottom, they are Khalid Sheikh Mohammed, Waleed Bin Attash, Ramzi Binalshibh, Ali Abd al-Aziz Ali, and Mustafa Ahmad al Hawsawi.

GUANTANAMO BAY NAVAL BASE, Cuba — A military judge is trying to decide whether the attempt to prosecute five prisoners at Guantanamo Bay for the Sept. 11 attacks can resume after stalling for nearly a year because of the revelation of an apparent FBI investigation into members of one of the defense teams.

The five defendants were expected back in court Monday for a hearing focused on whether more time is required to explore any potential conflict of interest arising from the questioning by FBI agents of defense team support staff.

The hearing came to an abrupt halt just minutes after it started. Defendant Ramzi Binalshibh told the judge that a new translator was someone he recognized from one of the CIA "black sites" overseas where he was held in secret detention and subjected to treatment widely considered torture during his interrogation.

"The problem is I cannot trust him because he was working at a black site with the CIA and you know I am from there," Binalshibh, a 42-year-old from Yemen who was captured in Pakistan in 2002, said in English.

Cheryl Bormann, a civilian lawyer for defendant Walid Bin Attash, then rose to say her client has "exactly the same issue" that she just learned upon entering the courtroom moments earlier.

"My client relayed to me this morning that there is someone in this courtroom who participated in his illegal torture," Bormann said.

The judge, Army Col. James Pohl, then called a recess, initially saying it would be for 15 minutes. Officials later said it would take at least an hour to resolve the issue.

The translators, one for each defendant, are civilian contractors hired by the government and all must have security clearances.

Among the issues under consideration this is week by Pohl to sever Binalshibh from the case to get it moving again toward an eventual death-penalty trial at the U.S. Navy base in Cuba.

Prosecutors want to keep all five together, arguing that separating the defendants would result in even more delays and cause further pain to relatives of those killed in the Sept. 11, 2001, terrorist attack.

"These are not circumstances that call for severance," the chief prosecutor, Army Brig. Gen. Mark Martins, told reporters at the base.

Keeping the case intact requires a finding by the judge that the FBI investigation did not create a conflict of interest for the defense attorneys for Binalshibh, whose team was the target of an investigation, the nature and scope of which have not been publicly disclosed.

James Harrington, the lead civilian attorney for Binalshibh, said the questioning of his staff has undermined the attorney-client relationship, crucial in a death penalty case. "Obviously, it's a major disruption in this case and it's also been a horrible disruption within my team," Harrington said on the eve of the hearing.

Lawyers say the fact that they or members of their staff could be under criminal investigation creates a potential conflict because it raises the possibility they could favor their own interest over that of their clients, easing up on their defense efforts.

Earlier, the judge appointed another lawyer to advise Binalshibh on the potential legal implications of the investigation, including whether Harrington can continue to represent him.

The revelation that FBI agents had members of Harrington's defense team, as well as staff on other teams, under investigation emerged in April, prompting an immediate halt to the fitful progress toward resolving pretrial issues in what officials have called the most expensive and complex criminal trial in U.S. history.

The five, who include the self-proclaimed mastermind of the Sept. 11 attacks, Khalid Sheikh Mohammed, were arraigned in May 2012 on charges that include terrorism, hijacking and nearly 3,000 counts of murder for their alleged roles planning and providing logistical support for the attack.

Defense Attorney James Connell told reporters that the trial is a long way off. "Not only is there no end in sight, there is no middle," he said.