NORTH CALDWELL, N.J. -- Federal officials said yesterday that a mail bomb that killed a prominent advertising executive Saturday was sent by the same man who has mounted a string of similar attacks since 1978, striking targets across the corporate and academic landscape in one of the most notorious unsolved crime sprees in the nation's recent history.
The suspect, described as an anarchist with a mastery of explosives and a grudge against the influence of technology in society, has long eluded a team of federal investigators that has roamed from Connecticut to California trying to track him down.
With the death on Saturday, the bomber, dubbed "unabom" because in the past he had seemed to want to torment universities and airlines, has now killed two men and wounded 23 other people in 15 attacks that are growing increasingly violent, officials said.
The officials said at a news conference yesterday that they had concluded that the explosion Saturday that killed Thomas Mosser, 50, an advertising executive, was related to the earlier ones because the bomb was built with similar materials and had a similar, sophisticated design.
"The components of the bomb, its construction, make us believe the bombs are linked," said Barry Mawn, the head of the FBI's Newark office.
But once again, they said they were not able to find a link between the latest victim and past victims.
Mr. Mawn said there was nothing to indicate that Mr. Mosser was involved with organized crime or had been a witness in a criminal trial. Nor, Mr. Mawn said, were there any threats made against him or his family in this wealthy suburb 15 miles from New York City.
Mr. Mawn said that from one brief sighting of the suspect and shards of evidence gathered at bomb scenes, the FBI had developed a likely profile of him. It identified him as a recluse, a white man in his late 30s or 40s with a high school education who is familiar with university life.
Investigators believe that he prides himself on the intricate construction of his bombs, crafting and polishing parts by hand even though they can be bought at a hardware store. In doing so, the suspect makes it harder to trace the parts' source.
The investigation into the bomber, who apparently mails his packages from Northern California, had stalled in the early 1990s until he resurfaced last year, maiming one professor in New Haven, Conn., and another in California.
After those incidents, investigators disclosed that he usually leaves the initials "FC" engraved on his bombs. Officials said yesterday that they had not yet determined whether those initials were on the bomb that killed Mr. Mosser.
The earliest victims of the attacks were airline executives. Those wounded in recent years have been scholars who have made significant advances in computer sciences, psychology and genetics.
Mr. Mosser, who was promoted to executive vice president earlier this year and recently was named general manager as well at Young & Rubicam, one of the largest advertising firms in the world, appears to be the first victim in advertising.
Mr. Mawn said investigators were examining the client list of Young & Rubicam and its public-relations subsidiary, Burson-Marsteller. Young & Rubicam has some technology clients, including Digital Equipment Corp. and Xerox.
Investigators said one reason Mr. Mosser might be linked to the other victims was that he was mentioned recently in the New York Times. At least three of the other victims, including the two last year, had been featured in articles in the Times that characterized them as leaders in their fields. An article on Mr. Mosser's promotion appeared Dec. 5.
The bomber sent a letter to the New York Times last year, postmarked Sacramento, Calif., identifying the author as "an anarchist group calling ourselves FC." The letter promised to "give information about our goals at some future time," a suggestion taken by investigators to mean that the suspect intended to attack again.
Mr. Mosser was killed about 11 a.m. when he opened a package the size of a videocassette that had been addressed to him, Mr. Mawn said.
The package had been delivered Friday in the regular mail and was handled repeatedly by Mr. Mosser's children and wife before he opened itwhile alone in the kitchen. Mr. Mosser was declared dead at the scene. Investigators said they had not yet ** determined where the package originated.
The first 12 bombings occurred from 1978 to 1987, beginning in Evanston, Ill., and ending in Salt Lake City. The suspect then took a six-year hiatus, officials said.
There is a a $1 million federal reward fund for information leading to the arrest of the suspect. The phone number is (800) 701-BOMB.