Washington(CNN) Nearly three years ago, John Brennan, acting CIA director at the time, found himself apologizing to the Senate intelligence committee and acknowledging that the CIA had spied on senators' computers after previously vehemently denying the claims.
Now, Brennan, who has been out of the role since January, is testifying about his own concerns about espionage from Russia via possible contacts with the Trump campaign.
In his most direct comments on the matter, Brennan told lawmakers on the House Intelligence Committee Tuesday that he had grown concerned last year that Moscow was trying to influence the Trump presidential campaign, saying, "Russia clearly had a preference for Trump."
Brennan had previously alluded to such fears, telling Fox News' Chris Wallace in mid-January that he didn't think then-President-elect Donald Trump has "a full appreciation of Russian capabilities, Russia's intentions," and that Trump's public displays of contempt for the US intelligence community could undermine national security. The remarks were made after Trump rejected intelligence agencies' reports of claims that Russia had compromising information on him.
Brennan, a top CIA official in the Bush administration, has found himself at the center of political controversy before, most notably over his changing points of view on torture.
As he sought confirmation as the agency's director under Obama, his positions as a torture skeptic were on full display, but he later gravitated to a staunch supporter of many interrogation practices -- a change that frustrated many Democrats.
During a rare 2014 news conference, Brennan defended harsh interrogation techniques as providing "useful" information to authorities, including intel used in the raid that led to the death of Osama bin Laden. But he said it is "unknowable" what information could specifically be attributed to those techniques.
Brennan's comments came shortly after a Senate panel released a blockbuster 528-page report detailing "enhanced interrogation techniques" -- including mock executions, "rectal rehydration," sleep deprivation and beatings -- in interrogations in the mid-2000s.
He admitted that some CIA officers' actions were "not authorized, were abhorrent and rightly should be repudiated by all. And we fell short in holding some officers accountable for their mistakes."
Brennan later lead an internal CIA overhaul to the agency's overall structure in 2015 in order to better deal with current threats -- a main focus being on cybersecurity.
In the unclassified version of a memo outlining the overhaul, Brennan said the changes were "driven by two fundamental shifts" in the current national security landscape - an increasing array of complex issues facing policy makers in Washington, as well as the "unprecedented pace and impact of technological advancements," the memo said.
Brennan, 61, is a New Jersey native who speaks Arabic and studied at the American University in Cairo, Egypt while earning an undergraduate degree from Fordham University. He later earned a master's in government from the University of Texas.
He joined the CIA in 1980, starting a career that saw him work as a Near Eastern and South Asian analyst, a Saudi Arabia station chief and leader of the agency's terrorism analysis. He was the CIA's daily intelligence briefer at the White House during President Bill Clinton's administration and served as former CIA Director George Tenet's chief of staff.
After serving as interim director of the National Counterterrorism Center, Brennan left government to become president of The Analysis Corporation, a security consulting firm.
During then-Sen. Barack Obama's 2008 presidential campaign, Brennan served as an intelligence adviser. Once Obama won, Brennan was considered a shoo-in for CIA director, but he withdrew his name amid criticism of his support for the use of torture in George W. Bush's administration.
Instead, he became Obama's deputy national security adviser. When the job of CIA director opened again in early 2013, Brennan was Obama's choice -- despite the concerns of left-leaning groups like the American Civil Liberties Union.
He was confirmed on a 63-44 vote and was sworn in on March 8, 2013.