WASHINGTON - When senior FBI officials announced plans in 2002 to participate with the CIA in terrorism-related interrogations abroad, some counterterrorism officials in the bureau balked, arguing vehemently against the idea.
To interrogate terrorism suspects with the CIA, they warned, could diminish the FBI's ability to abide by the legal protections the United States grants defendants. The officials raised concerns that the CIA's techniques were too severe and perhaps unethical, current and former bureau officials say.
FBI Director Robert S. Mueller III and other top officials did not heed the warnings. Starting with the capture of Abu Zubaida, a top lieutenant of Osama bin Laden, in April 2002, the FBI forged into uncharted territory, joining the CIA to interrogate detainees at Abu Ghraib prison and elsewhere.
Now, two years later, the bureau has landed in a minefield of legal issues. The result could affect bureau credibility among potential jurors and taint terrorism cases it has built. FBI agents frequently testify in criminal trials, unlike CIA operatives, who need to preserve their secrecy.
The bureau is trying to distance itself from the CIA and allegations that CIA interrogators took part in abuses, possibly including cases that led to the deaths of two detainees. FBI officials say a bureau inquiry has so far turned up no evidence of abuses, or knowledge of any, by FBI agents.
The CIA has referred three cases, including the two deaths, to the Justice Department for review. The department and the Pentagon are trying to determine whether the cases should be investigated criminally by Justice or handled in military courts.
The FBI's foray into terrorism interrogations abroad began with Zubaida, while a debate on the issue was raging within the bureau, current and former officials said. One top official involved in the discussions told the FBI director and his staff, "We need to keep the FBI out of this," according to the official.
But the CIA's interrogation of Zubaida was turning out to be one of the most successful yet in the war on terrorism - so much that some bureau officials began to feel they would risk ceding authority over domestic terrorism if they didn't participate. Among the information Zubaida's interrogators gleaned was that a U.S. citizen, Jose Padilla, who has since been charged, was possibly plotting to set off a radioactive "dirty bomb" in the United States.
Having been excoriated for not working more closely with the CIA on counterterrorism before Sept. 11, the FBI was under pressure to collaborate. Mueller and his staff called for the integration of bureau agents into CIA interrogations abroad, a first in the bureau's history.
"It was a very touchy issue," a former official said. "The real problem was the possible ethical situations" arising from the CIA's techniques.
Mueller testified Thursday before the Senate Judiciary Committee that he told FBI agents to remain apart from any interrogations that seemed to veer into abuse - and to report any abusive interrogations.
His agents abroad, Mueller testified, abide by the same laws and standards that bar mistreatment of prisoners in the United States.
The Wall Street Journal reported, though, that an FBI agent may have witnessed abuses. The Journal said the agent approached a Red Cross investigator in Iraq and told the investigator in confidence, "You guys have to start working on the Abu Ghraib problem."
An FBI official said the bureau has no knowledge of such an encounter.
"There was a survey done of each agent assigned to Iraq, asking if anybody was aware of any abuse," the official said. "Thus far, every answer has been no.
"We're still investigating," the official said.
Some FBI officials now say they wish they had not become involved with the CIA. The bureau is involved in joint interrogations with CIA agents in Afghanistan, Guantanamo Bay, Cuba, and Iraq, including at Abu Ghraib, officials said.
The bureau has also jointly interrogated Saddam Hussein. The CIA has reduced its role in the Hussein interrogation, bureau sources said. The CIA had focused mostly on determining whether Hussein possessed weapons of mass destruction. The FBI is now largely involved in building a case of war crimes against the former dictator.
Other FBI agents, a senior official said, are in remote parts of Afghanistan, scouring the terrain with CIA agents.
At stake now is the bureau's ability to retain credibility with jurors, whether in a terrorism-related trial abroad or a bank robbery in Kansas, that they do not beat confessions out of defendants or torture innocent people into making seemingly guilty admissions. Some bureau officials fear they could be found guilty by association.
"Traditionally, the CIA and FBI avoided that kind of joint interrogation," said Melvin Goodman, a senior fellow at the Center for International Policy and a veteran of the CIA. "Even in spy cases, it was separate. If someone was recruited by the FBI, he would be interrogated by them and then turned over" to the CIA for debriefing.
Goodman said the CIA's use of aggressive techniques in interrogations has expanded over the years as the agency has recruited more former special operations officers from the military.
The CIA's interest in having the FBI take part in joint interrogations stemmed, in part, from the Bush administration's early desire to prosecute suspected terrorists in criminal trials, current and former officials of both agencies said. The CIA did not want to be dragged into court to testify about what a detainee had confessed. The solution was to invite FBI agents, who are trained to conduct cases with the understanding that their role is to testify, to join the interrogations.
If any agent were to witness abuse of a suspect, one FBI official noted, the agent could not then testify against the suspect, and his or her credibility could be tarnished indefinitely. And "if an agent can't testify, it diminishes the agent's ability to perform as an agent - even 20 years from now."
The bureau could soon face a crisis over the handling of information it has collected from interrogations.
"Any evidence taken at Abu Ghraib is worthless in court," said James X. Dempsey, director of the Center for Democracy and Technology and former staff counsel for the Senate Judiciary Committee in charge of FBI oversight.
"That and any information from Afghanistan and maybe even Guantanamo. They headed down this road, and now the whole operation is a disaster from a national security standpoint, not to mention a human rights perspective."
For now, the bureau is doing what it can to separate its activities from CIA interrogations.
Reading from a prepared statement before Congress this week, Mueller conspicuously skipped over a paragraph.
It began, "The FBI and the CIA are integrated at virtually every level of our operations."