Nope, I didn't know this either:Well, in fact, I had heard of it. I read about it when Buckley was making the case that Smith had been wrongfully convicted, and I read about it when Smith reoffended and was arrested.(This is because my misspent youth was a conservative misspent youth, and I read NR and the Buckley anthologies yearly.)
Back in 1957, a guy named Edgar Smith was convicted of murdering a 15-year-old girl. It only took a jury under three hours to declare him guilty, and he was sentenced to death. Somehow, he wound up in correspondence with conservative commentator William F. Buckley (the founder of the National Review).
Buckley worked for years to get Smith released until, in 1971, he was.
After his release, Smith appeared on Buckley's talk show and collected $1,000 speaking fees touring college campuses around the nation. All was well until five years later, when he abducted seamstress Leftiriya Ozbun while she was going home from work. The girl survived, but Smith is back in prison, serving a life sentence.
He called Buckley for help of some kind, and Buckley immediately and very properly called the FBI.
But Buckley, for all his faults, wasn't Norman Mailer. It was only his misguided belief that Smith was innocent that had him fighting to get him off death row—Mailer thought guys like Abbott should be allowed out even though they were guilty.
And it's quite possible he wouldn't have called the FBI.
Buckley was foolish to believe Smith, (the case is mentioned in a book called Annals Of Gullibility,) but Mailer, who got psychopath Jack Henry Abbott released from jail in order to come to New York and be a writer,actually supported crime in principle,writing:"The psychopath murders—if he has the courage —out of the necessity to purge his violence, for if he cannot empty his hatred then he cannot love, his being is frozen with implacable self-hatred for his cowardice."
You can read about the Smith cases in Crime Magazine: The Great Prevaricator.
That's where I got the image above of Smith appearing on Firing Line.