F.B.I. Says Fatal Mail Blast Is Work of Serial Bomber
15th Attack Since '78 Kills New Jersey Executive

Federal officials said today that a mail bomb that killed a prominent advertising executive here on 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 death of the executive in this wealthy suburb about 15 miles from New York City deepened the mystery of the bomber. 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 today in Newark that they had concluded that the explosion that killed the executive, Thomas J. Mosser, 50, was related to the earlier ones because the bomb was built with similar materials and had a similar, sophisticated design. But once again, they said they were not exactly certain what connected Mr. Mosser to the other victims.

"The components of the bomb, its construction, make us believe the bombs are linked," said Barry Mawn, the head of the F.B.I.'s Newark office.

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.

Mr. Mawn said that from one brief sighting of the suspect and shards of evidence gathered at bomb scenes, the F.B.I. had developed a likely profile of him. It identified him as a recluse, a white man in his late 30's or 40's 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 where the parts came from.

The investigation into the bomber, who apparently mails his packages from northern California, had stalled in the early 1990's until he resurfaced last year, maiming one professor in New Haven and another in California. After those incidents, investigators disclosed that he usually leaves the initials "FC" engraved on his bombs. Officials said today 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, for which Mr. Mosser served as chief operating officer until he was promoted. Young & Rubicam has some technology clients, including the Digital Equipment Corporation and Xerox. It also works for the United States Postal Service, Philip Morris, KFC, Kraft General Foods and several other conglomorates.

Investigators said one reason Mr. Mosser might also 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 describing Mr. Mosser's promotion appeared in The Times on Dec. 5.

Mr. Mosser's address and phone number are listed in the local telephone directory.

The bomber sent a letter to The 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.

Senior law-enforcement officials said today that they hoped that the bomber would again communicate with The Times or another newspaper about the most recent incident because it might provide clues as to what had happened.

Mr. Mosser was killed about 11 A.M. on Saturday at his home on 15 Aspen Drive when he opened a package the size of a videocassette that had been addressed to him, Mr. Mawn said. The package had been delivered on Friday in the regular mail and was handled repeatedly by Mr. Mosser's wife and at least one of his children before he opened it a day later, while alone in his kitchen.

Investigators said they had not yet determined where the package originated.

The explosion tore a hole through a kitchen counter, broke windows and filled the room with smoke. Mr. Mosser was declared dead at the scene, and was apparently decapitated by a bomb that appeared to be stronger the any of those mailed to earlier victims, officials said.

"It didn't sound like something had fallen, it sounded serious," said Robin Sommese, 13, who was in the house, along with several other children, for a party when the bomb exploded. "There was no fire, but there was plenty of smoke."

The only known sighting of the bomber was in Salt Lake City in 1987, when a witness saw a man place a bomb behind a computer store, said Rick Smith, a spokesman for the F.B.I. office in San Francisco, which has a task force of 25 investigators and support personnel that is spearheading the investigation. The bomber was described as a white man with a ruddy complexion and blond to red hair. He was wearing a hooded sweatshirt.

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 for unknown reasons, officials said.

Before the letter sent to The Times, the bomber had never explained his motives, though in a few instances he had sent messages to his victims in the weeks before he attacked. He sent a letter to an airline executive, telling him to read a book that would be arriving in the mail. He asked a professor to read a forthcoming manuscript.

Federal agencies, including the Federal Bureau of Investigation, the Postal Service and the Bureau of Alcohol, Tobacco and Firearms, have set up a $1 million reward fund for information leading to the arrest of the suspect. The phone number is (800) 701-BOMB.

CHRONOLOGY

15th Link in a Bombing Chain Federal authorities said yesterday that a package bomb that killed an executive at his home in New Jersey on Saturday was linked to 14 other bombings or attempted bombings since 1978. There have been two deaths in the explosions.

MAY 25, 1978 Northwestern University, Evanston, Ill. Bomb placed in unmailed parcel explodes, injuring a security guard.

MAY 9, 1979 Northwestern University. Bomb placed in Tech Building explodes; one injury.

NOV. 15, 1979 American Airlines Flight No. 444 en route from Chicago to Washington. Bomb explodes in mailbag aboard Boeing 727, causing 12 smoke inhalation injuries.

JUNE 10, 1980 Lake Forest, Ill. Bomb injures Percy Wood, president of United Airlines, as he opens package mailed to his home.

OCT. 8, 1981 University of Utah in Salt Lake City. Bomb placed in a business classroom explodes; no injuries.

MAY 5, 1982 Vanderbilt University, Nashville. Bomb mailed to head of computer science department explodes, injuring secretary.

JULY 2, 1982 University of California at Berkeley. Bomb placed in coffee break room in Cory Hall explodes; electrical engineering professor is injured.

MAY 15, 1985 University of California at Berkeley, Bomb placed in a computer terminal room in Cory Hall explodes; student severely injured.

MAY 18, 1985 Boeing Company, Auburn, Wash. Bomb mailed to fabrication division is dismantled after employees realize package contains explosive.

NOV. 15, 1985 University of Michigan in Ann Arbor. Bomb mailed to a psychology professor's home explodes, injuring research assistant.

DEC. 11, 1985 Sacramento, Calif. Bomb left behind computer rental store explodes, killing the owner, Hugh Campbell Scrutton.

FEB. 20, 1987 Salt Lake City. Bomb in bag explodes in parking lot of computer sales and service firm; employee maimed.

JUNE 22, 1993 Tiburon, Calif. Bomb injures Dr. Charles J. Epstein, geneticist at the University of California at San Francisco, as he opens package mailed to his home.

JUNE 24, 1993 Yale University, New Haven. Bomb injures David Gelernter, a computer scientist, as he opens package mailed to his office.

DEC. 10, 1994 North Caldwell, N.J. Parcel mailed to home of Thomas J. Mosser, 50, general manager of Young & Rubicam in Manhattan, explodes when he opens it, killing him.