WASHINGTON — A long-simmering dispute between the CIA and its Senate overseers erupted into public view Tuesday when the head of the Senate Intelligence Committee accused the agency of possible crimes and of attempting to intimidate committee staffers investigating the CIA's former use of waterboarding and other harsh interrogation techniques.
Sen. Dianne Feinstein (D-Calif.), the committee chairwoman, said the CIA secretly searched computers used by Senate staffers and might have violated constitutional provisions on separation of powers and unreasonable searches, a federal law on computer fraud and abuse, and a presidential order that prohibits the CIA from domestic searches and surveillance.
"I am not taking it lightly," the normally strong advocate for U.S. intelligence agencies warned on the Senate floor.
Several hours later, CIA Director John Brennan denied that the CIA had spied on the Senate oversight committee or had hacked its computers.
"Nothing could be further from the truth," Brennan said in a previously scheduled event at the Council on Foreign Relations. "We wouldn't do that. That's just beyond the scope of reason."
Brennan did not deny that the agency had audited activity logs of classified computers that Senate investigators used at a secure CIA facility to review 6.2 million pages of CIA operational cables, internal emails, memos and other documents relating to the agency's now-closed detention and interrogation program.
The CIA data search in January sought to determine how the Senate staffers had obtained and copied a sensitive internal document in 2010 that the CIA insists the staffers were not entitled to see.
The CIA has referred its own conduct and that of the Senate staffers to the Justice Department for possible criminal investigation, officials said. It's unclear whether Justice Department lawyers have begun a review.
"Appropriate authorities right now ... are looking at what CIA officers as well as [Senate] staff members did," Brennan said.
Feinstein said she had sought an apology and an official acknowledgment that the CIA search of Senate computers was inappropriate. "I have received neither," she said.
She called the dispute a "defining moment" for congressional oversight of intelligence agencies, which already are under intense criticism for former National Security Agency contractor Edward Snowden's leaks about domestic and foreign surveillance systems.
The exchanges widened a rift between the CIA and the Senate committee, which was created in the 1970s in the aftermath of widespread abuses by America's spy services. Democrats rushed to support Feinstein, while most Republicans on the committee remained mute, with some saying privately that the case was more complicated than Feinstein portrayed it.
Two defense hawks, Sens. Lindsey Graham (R-S.C.) and John McCain (R-Ariz.), slammed the CIA, however. "If true, this is Richard Nixon stuff," Graham said, suggesting those responsible should be fired.
The clash put the White House in an awkward position, caught between an agency that reports to the president and a powerful veteran Democrat. White House spokesman Jay Carney said he could not comment on Feinstein's charges because the Justice Department is considering the case.
If evidence of improper action is found, the White House "would support getting to the bottom of it," he said. "The president has great confidence in John Brennan and confidence in our intelligence community and in our professionals at the CIA."
The dispute emerged from the committee's investigation of the CIA's use of mock drowning, sleep deprivation and other so-called enhanced techniques after the terrorist attacks of Sept. 11, 2001. After a five-year review, the committee approved a 6,300-page report in December 2012, but it has not been declassified for release.
According to officials who have read the report, it concludes that the techniques produced little useful intelligence and were far more brutal than agency officials acknowledge. The CIA and some Republicans on the committee don't agree.
Feinstein said Tuesday that the report contained "the horrible details of a CIA program that never, never, never should have existed."
During the investigation, Feinstein said, Senate staffers using a CIA-issued data search tool had discovered drafts of an internal review, originally commissioned by then-CIA Director Leon E. Panetta, that acknowledged "significant CIA wrongdoing" and corroborated critical parts of the committee report rather than the CIA's formal response.
She said staffers didn't know whether the Panetta documents were "provided intentionally by the CIA, unintentionally by the CIA or intentionally by a whistle-blower."
Staffers printed copies of the drafts and took them to the Senate committee's secure area in the Hart Senate Office Building.
That was legal and wise, Feinstein said. She noted that in 2005, senior CIA officers had destroyed videotapes of the waterboarding and other harsh interrogations over the objections of the Bush White House and the director of national intelligence. In 2010, she said, the CIA had repeatedly removed documents that committee investigators sought to examine.
"There was a need to preserve and protect" the Panetta review documents, she said.
She said the staffers had the appropriate security clearances, had handled the classified material properly and were provided access to the documents by the CIA itself.
The CIA viewed the removal as a security breach, insisting that the investigators had agreed not to take copies from the CIA facility. Republican committee aides, speaking on condition of anonymity, say staffers need to honor such agreements to maintain access to sensitive CIA documents.
Feinstein also sharply criticized the CIA's acting general counsel, Robert Eatinger, who she said had alleged to the Justice Department that Senate staffers may have committed a crime.
Without naming Eatinger, she said the acting general counsel had been a lawyer in the CIA's Counterterrorism Center, which managed and carried out the interrogation program from mid-2004 until it officially ended in January 2009.
"He is mentioned by name more than 1,600 times in our study," Feinstein said.
"And now this individual is sending a crimes report to the Department of Justice on the actions of congressional staff — the same congressional staff who researched and drafted a report that details how CIA officers — including the acting general counsel himself — provided inaccurate information to the Department of Justice about the program."
In a message to CIA employees late Tuesday, Brennan said that the agency has tried to cooperate with the Senate investigation and that it agrees with some findings in the report and disagrees with others.
The CIA has "taken corrective measures to prevent such mistakes from happening again," he wrote. "But we also owe it to the women and men who faithfully did their duty in executing this program to try to make sure any historical account of it is balanced and accurate."
Lisa Mascaro in the Washington bureau contributed to this report.