G Gordon Liddy, one of the masterminds of the Watergate burglary who became a radio show host after his release from prison, has died at the age of 90.
His son, Thomas Liddy, confirmed his father's death and said only that it was not Covid-19-related, US media say.
Liddy remained unapologetic for his part in the plan to bug the Democrats' HQ at the Watergate building during the Republicans' 1972 re-election campaign.
The scandal led to the resignation of then President Richard Nixon.
Born George Gordon Battle Liddy in New Jersey in 1930, he is said to have been a frail boy who was inspired by the rousing radio speeches of Adolf Hitler that residents in his German American neighbourhood were listening to at the time.
"If an entire nation could be changed, lifted out of weakness to extraordinary strength, so could one person," he wrote in his autobiography Will, recalling how he roasted and ate a rat at the age of 11 in order to overcome his fear of rodents.
Having served in the army and graduated from law school, Liddy joined the FBI and eventually moved to the White House to help with Richard Nixon's re-election campaign.
Some of the extreme ideas he, and colleague Howard Hunt, a former CIA officer, came up with - from plotting to kill Nixon critics to kidnapping anti-war protesters - never got the go-ahead, but their plan to bug the Democratic National Committee offices did.
But the botched burglary, cover-up, and subsequent investigation snowballed into one of America's biggest political scandal.
Liddy, Hunt and five others were arrested and faced charges of conspiracy, burglary and illegal wiretapping. Liddy was the only one who refused to cooperate with the prosecution. He was sentenced to 20 years and served nearly five years before his sentence was commuted in 1977 by Democratic President Jimmy Carter.
Years later, Liddy said: "I'd do it again for my president." He drove a Rolls Royce with the numberplate H20GATE.
After his release from prison, he started a security firm, wrote best-selling books and became a popular and provocative conservative talk show host.