LINCOLN, Mont. — Investigators preparing to file major criminal charges against Theodore J. Kaczynski assembled bits of forensic evidence Tuesday that sources say tie him more firmly to the string of 16 bombings carried out by the Unabomber since 1978.
Specifically, the sources said, technicians have found similarities between a completed bomb found in Kaczynski's Montana cabin over the weekend and an explosive device used in one of the more recent lethal attacks.
But a source cautioned that extensive testing at FBI laboratory facilities in Washington, D.C., and Quantico, Va., must be conducted before federal officials can conclusively determine that the Unabomber used the same bomb-making technique as the person who built the device found at the former math instructor's 10-by-12-foot cabin.
Technicians also have found tools, including wire cutters and wood-carving instruments, that authorities say appear to have left telltale marks on fragments recovered from some of the bombings.
In other developments Tuesday:
* Sources said investigators have discovered "something big" in the form of evidence that is more conclusive than anything yet disclosed. While sources refused to describe the nature of the evidence, they did say it is related to a single incident. One source said that evidence contains more than one item.
* Authorities discounted reports that the names of some bombing victims had been found in documents at Kaczynski's primitive home. "There's a name on a piece of paper and some other stuff on it," a federal source said, but it "was a generic name."
He declined to say what he meant by generic but left open the possibility the name was indirectly linked to a victim, such as the name of a corporation, employer or business, rather than an individual.
Another source said the name was even more general and referred to an "industry type."
* A letter published Tuesday provided a glimpse into Kaczynski's eccentric personality more than 20 years ago. The letter was sent in 1974 by Kaczynski to the owner of a gas station outside Great Falls, Mont., where the former UC Berkeley professor apparently worked for a short time.
In the letter, Kaczynski referred to the gas station owner as a "fat con-man" and threatened to bring legal action against him if he did not pay money Kaczynski claimed he was owed. The station owner, Joe Visocan, has turned it over to the FBI and released a copy to the Great Falls Tribune, which published it in Tuesday's edition. Visocan said he has no recollection of Kaczynski but kept the letter because it was so unusual.
* And in what could be a connection between Kaczynski and one of the Unabomber's victims, University of California officials confirmed Tuesday that Hugh Scrutton, who was killed by a bomb in 1985 in Sacramento, had attended classes at UC Berkeley when Kaczynski may have been on campus.
UC Berkeley spokeswoman Marie Felde said Scrutton, a math major at UC Davis, completed a summer session at Berkeley from late June through August 1967. Kaczynski was added to the UC Berkeley payroll on July 1, 1967, Felde said, though he did not begin teaching in the math department until late September.
UC Davis officials said Scrutton's transcript showed he took four classes while at Berkeley--only one of which, "History of Mathematics," involved the math department. The other three courses were on computer science, anthropology and philosophy.
But whether Kaczynski and Scrutton even were on campus at the same time remains unclear. "They could have come in contact," Felde said. "The key is to find out when Kaczynski showed up in Berkeley."
Federal agents have turned up similarly tentative evidence that Kaczynski may have been in a position to cross paths with three other victims.
Among the tentative links between Kaczynski and Unabomber victims: United Air Lines President Percy Wood, wounded in a 1980 bombing, was a member of the Bay Area Air Pollution Control Board advisory committee when Kaczynski was teaching at Berkeley. Patrick Fisher, a Vanderbilt University computer science professor whose secretary was wounded by a 1982 bomb, is the son of a math professor who taught at the University of Michigan when Kaczynski was a graduate student in that department. Fisher visited his father there and may have encountered Kaczynksi. And James McConnell, who narrowly avoided injury in a 1985 attack, was a psychology professor at the University of Michigan when Kaczynski was a student there.
Meantime, former FBI officials differed in their evaluation of the weekend discovery of the completed bomb with batteries in place. Oliver B. "Buck" Revell, the former third-ranking official at the bureau who oversaw the Unabom probe for several years, said that if Kaczynski is the Unabomber, the device may be a sign that he was going to strike again.