G. Gordon Liddy, however WAS convicted of a crime:

Liddy has acknowledged preparing to kill someone during the Ellsberg break-in "if necessary"; plotting to murder journalist Jack Anderson; plotting with a "gangland figure" to murder Howard Hunt to stop him from cooperating with investigators; plotting to firebomb the Brookings Institution; and plotting to kidnap "leftist guerillas" at the 1972 Republican National Convention -- a plan he outlined to the Nixon administration using terminology borrowed from the Nazis. (The murder, firebombing, and kidnapping plots were never carried out; the break-ins were.)
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Liddy has donated $5,000 to McCain's campaigns since 1998, including $1,000 in February 2008. In addition, McCain has appeared on Liddy's radio show during the presidential campaign, including as recently as May.

John McCain's appearance on The G. Gordon Liddy Show 11/8/07 includes a discussion between Liddy and McCain, whom Liddy described as an "old friend." During the segment, McCain praised Liddy's "adherence to the principles and philosophies that keep our nation great," said he was "proud" of Liddy, and said that "it's always a pleasure for me to come on your program."

Additionally, in 1998, Liddy reportedly held a fundraiser at his home for McCain. Liddy was reportedly scheduled to speak at another fundraiser for McCain in 2000. The Charlotte Observer reported on January 23, 2000, that McCain's campaign vouched for Liddy's "character":