A CIA panel found that “no disciplinary actions are warranted” for agency lawyers and computer experts who were involved in searching computers that were used by congressional aides in a probe of the CIA’s counterterrorism interrogation tactics. (Saul Loeb/AFP/Getty Images)

An internal CIA panel concluded in a report released Wednesday that agency employees should not be punished for their roles in secretly searching computers used by Senate investigators, a move that was denounced by lawmakers last year as an assault on congressional oversight and a potential breach of the Constitution.

Rejecting the findings of previous inquiries into the matter, the CIA review group found that the agency employees’ actions were “reasonable in light of their responsibilities to manage an unprecedented computer system” set up for Senate aides involved in a multiyear probe of the CIA’s treatment of terrorism suspects.

The agency panel, which was led by former U.S. senator Evan Bayh (D-Ind.), cited a lack of clear ground rules between the CIA and the Senate, and it faulted CIA workers for missteps including reading e-mails of congressional investigators.

But while such transgressions were “clearly inappropriate,” Bayh said in a statement released by the CIA, they “did not reflect malfeasance, bad faith, or the intention to gain improper access” to sensitive Senate material.

The findings are at odds with the conclusions reached by the CIA’s inspector general in a separate review last year and were quickly dismissed by lawmakers including Sen. Dianne Feinstein (Calif.), the top Democrat on the Senate Intelligence Committee, who led the investigation of the interrogation program.

“Let me be clear: I continue to believe CIA’s actions constituted a violation of the constitutional separation of powers,” Feinstein said in a written statement. She noted that CIA Director John O. Brennan had previously apologized for the dispute but said she was “disappointed that no one at the CIA will be held accountable.”

The CIA also released a redacted version of the IG’s investigation, which found that five CIA employees had “improperly accessed” Senate files but also places new blame on congressional aides. It also disclosed that one person assigned to the committee from the office of the Director of National Intelligence was fired in 2010 after sneaking a camera into an office where Senate investigators had access to millions of classified files.

The newly released documents provide the most detailed accounts to date of the cloak-and-dagger behavior that triggered an extraordinary feud last year between the CIA and one of two congressional panels charged with overseeing agency conduct.

The conflict centered on allegations of computer hacking and snooping, but it was in many ways a proxy for a higher-stakes fight over the Senate’s long-running investigation of the CIA’s use of torture on terrorism suspects after the attacks of Sept. 11, 2001.

After years of delay, the Senate panel finally released its report last month, delivering a searing account of CIA brutality and accusing the agency of repeatedly exaggerating the effectiveness of its methods. The report was based on a review of millions of classified CIA memos conducted by Senate investigators who worked for years at a secret CIA facility in Northern Virginia.

The Bayh-led panel was set up after that fight had burst into public view. The panel was charged with determining whether any of the five CIA employees identified in the IG’s report should face discipline. But the “accountability review board” concluded that the CIA-Senate arrangement was so convoluted that the panel could find no clear rules on how the shared computer system was to be run, let alone whether any rules had been violated. In addition to Bayh, the panel included former White House counsel Robert F. Bauer and three senior CIA officers who have not been identified.

The panel focused its inquiry on a series of CIA searches of a computer system that was supposed to enable the CIA to turn over documents being demanded by the Senate committee but inadvertently enabled congressional investigators using basic search tools to find files on overlapping networks that were supposed to remain off-limits.

In 2010, Senate principal investigator Daniel Jones discovered a document that had been commissioned by then-director Leon E. Panetta to catalogue the files being provided to Congress and assess how damaging they might be.

As tensions with the CIA mounted, the Panetta review seemed to grow in importance, being seen by some lawmakers as proof that the agency agreed with some of the Senate’s findings about the failings and abuses in the interrogation program.

Jones removed portions of that Panetta review document in 2013, making copies that were secretly taken back to Senate offices. When the agency realized the committee had obtained the document, it set out to find out how.

Bayh’s report indicates that Brennan encouraged the effort, saying the director pressed subordinates to determine whether there had been a breach and making clear “his desire to confront [Senate committee] leadership immediately with information concerning the matter.”

CIA experts then searched the Senate system on at least three occasions, according to the report, which described the last intrusion as “the source of greatest controversy” because it involved not only looking for CIA files but also reading e-mails of Senate aides.

This “third look resulted in inappropriate access” to Senate files, the panel found, but the report described the material as “five e-mails, none of any consequence or involving discussions of substantive matters” and said the decision to access them warranted no punishment.

Brennan had at one point issued a “stand-down” order to halt the searches and had sought to open a joint inquiry with the Senate, but his instructions failed to reach some involved in the probe.

The review group focused on only five CIA employees — two senior attorneys at the agency and three computer specialists. While acknowledging that constraint, a person familiar with the panel’s deliberations said it had had broad access and saw no evidence that others beyond the five had engaged in misconduct.

The group also dismissed the IG’s finding that certain employees had “demonstrated a lack of candor” in describing their roles in the computer search, saying there were no recordings of those interviews or other evidence to substantiate the claim.

Overall, the panel’s findings suggest that it uncovered deep problems with the work of CIA Inspector General David B. Buckley, who is to leave that job at the end of the month. CIA spokesman Dean Boyd said Buckley’s departure had been planned for months and is unrelated to the competing probes.

Adam Goldman and Julie Tate contributed to this report.