CIA inspector general David Buckley, who investigated a dispute between the agency and Congress regarding the handling of records of the CIA's detention and interrogation activities, is resigning effective Jan. 31, the CIA said on Monday.

Buckley, who had served as the agency's internal watchdog for more than four years, is leaving the agency to "pursue an opportunity in the private sector," the CIA said in a statement.

Officials at both the CIA and on Capitol Hill said his departure was unrelated to politics or anything he had investigated.

Buckley's office last July issued a report on a dispute between the CIA and the Senate Intelligence Committee. The report found that some agency employees had "acted in a manner inconsistent" with an understanding between the CIA and the committee regarding access to a special computer network set up to share documents about the agency's involvement in harsh treatment of detained militants.

According to the report, CIA director John Brennan a year ago complained to the Senate Intelligence Committee's leadership, then headed by Democratic Sen. Dianne Feinstein, that Senate investigators had obtained documents to which the agency believed they should not have had access.

Subsequently, according to an agency statement, Feinstein expressed concern that CIA officers acted improperly when they searched the special computer network to locate the documents.

Buckley's office reported "a judgment that some CIA employees acted in a manner inconsistent with the common understanding" about access to the network which the Senate panel and agency had reached in 2009, a CIA statement said.

Buckley's office sent its report on the dispute to the Justice Department. Meanwhile, the CIA's acting general counsel filed a criminal referral with the Justice Department complaining about the actions of Senate investigators.

The Justice Department later decided that it had insufficient grounds to open a full-scale investigation into either the inspector general or the general counsel's complaints.

Buckley, who served both as a senior official in the Treasury and Defense Departments as well as in senior positions at the Senate Intelligence Committee and the Government Accountability Office, was praised by both CIA colleagues and the White House.

CIA director John Brennan said that during his tenure, Buckley had "demonstrated independence, integrity, and sound judgment in promoting efficiency, effectiveness, and accountability."

A White House official said that Buckley had been "a tremendous partner to colleagues throughout the Administration." It was not immediately known what Buckley's new role in the private sector would be.

Reuters