Another bomb two days later killed Robert E. Robinson, an African-American lawyer in Savannah, Ga. Officials also intercepted a device that was sent to the 11th Circuit’s offices in Atlanta, as well as a bomb that was mailed to a Florida office of the N.A.A.C.P.

Prosecutors believed Mr. Moody disguised his motive by using the name of a fictitious group when he vowed to kill judges and railed against African-Americans and the Atlanta-based 11th Circuit’s treatment of them.

Federal officials began to focus on Mr. Moody after an investigator described one of the bombs to a chemist with what was then known as the Bureau of Alcohol, Tobacco and Firearms, who sketched the device on a napkin and noticed its similarity to one Mr. Moody had built in 1972.

“That’s Moody’s bomb,” the chemist said in an episode Mr. Freeh described in his memoir, which noted that Mr. Moody’s companion ultimately cooperated with investigators and provided crucial information.

Mr. Moody, who attended law school and apparently resented that he could not practice, has maintained his innocence. In a recent letter to Judge Vance, he wrote, “Had my Dad been murdered, I would want to know who had done it.”

Yet federal officials long pointed to a recording, partly transcribed in a court ruling, of Mr. Moody talking to himself in jail after the killings: “Now you’ve killed two. … Now you can’t pull another bombin’.”

“I never came across someone like him: very brilliant, very determined, very skillful,” Mr. Freeh recalled on Thursday, adding, “He made it a campaign to declare war against the courts and kill these innocent people, but I’ve never seen a defendant like that.”