For 17 years, the Unabomber has been elusive and shrewd, leaving tantalizingly few clues for authorities to track.
But since the Oklahoma City bombing, he's sent out a flurry of letters to national media, including a request that The New York Times and The Washington Post publish his 35,000-word personal political manifesto."He is whipped up with all the publicity, he's on a roll. He's at the very peak of his career," said Michael Rustigan, a criminologist at San Francisco State University.
"Look what one little note to the San Francisco Chronicle did for him," Rustigan said, referring to the bomber's letter last week threatening to blow up a Los Angeles airliner by July Fourth.
"His note generated tons of publicity. He's on a high from that. He was in the minor leagues then, now he's a national guy."
Despite a second note to The New York Times calling the first threat a prank, security remained tight at Los Angeles International Airport.
About 650,000 passengers were expected to pass through the airport during the four-day holiday weekend ending Tuesday night.
National Transportation Secretary Federico Pena said that he, his wife and two children have flown out of the airport since tighter security was imposed. He insisted that air travel is safe but declined to say when the restrictions might be lifted.
"We will keep the security measures in place until the matter is resolved," he told CNN on Sunday.
The Unabomber, so-named by the FBI because many of his early victims were connected to universities and airlines, has killed three people and wounded 23 in 16 package bombings since 1978.
On Friday, a professor at the University of California, Berkeley, received a package from the Unabomber containing documents similar to the ones received by the Times and the Post last week, FBI spokesman George Grotz said.
"What's encouraging is that he has decided to communicate via the written word as opposed to planning any more bombs," Grotz said.