Former White House aide I. Lewis ‘Scooter’ Libby, right, is escorted to a waiting vehicle with his attorney, Theodore Well, left, outside federal Court in Washington, Thursday, June 14, 2007. (AP Photo/Pablo Martinez Monsivais)

WASHINGTON (AP) — President Donald Trump issued a full pardon Friday to I. Lewis “Scooter” Libby, a former top aide to Vice President Dick Cheney.

Trump said he does not know Libby, but “for years I have heard that he has been treated unfairly. Hopefully, this full pardon will help rectify a very sad portion of his life,” according to a statement issued by White House spokeswoman Sarah Huckabee Sanders announcing the pardon.

Libby, Cheney’s former chief of staff, was convicted of lying to investigators and obstruction of justice following the 2003 leak of the covert identity of CIA officer Valerie Plame. President George W. Bush later commuted Libby’s 30-month prison sentence, but didn’t issue a pardon despite intense pressure from Cheney. No one was ever charged for the leak.

Since then, the Libby case has been criticized by conservatives, who argue he was the victim of an overly zealous and politically motivated prosecution by a special counsel. Another twist is that the special counsel, Patrick Fitzgerald, was appointed by James Comey, deputy attorney general at the time. Comey later became head of the FBI, but was fired by Trump, and has since written a book highly critical of the president.

White House counselor Kellyanne Conway, while declining at the time to confirm Trump’s plans for a pardon, said earlier Friday that “many people think that Scooter Libby was the victim of a special counsel gone amok.” Asked if a pardon would be about Comey, Conway said no.

Plame appeared on MSNBC Friday morning and said a pardon would send a message “that you can commit crimes against national security and you will be pardoned.”

The pardon was the third for Trump. He granted one last year for former Arizona sheriff Joe Arpaio, who was awaiting sentencing for contempt of court. Trump also pardoned a U.S. Navy sailor, who was convicted after taking photos of classified portions of a submarine.

Conservative criticism of the special counsel in the Plame case echoes critiques of Robert Mueller, the special counsel leading an investigation into Russian election interference, possible coordination with Trump associates and potential obstruction of justice by the president. Trump has called that probe a “witch hunt.”