LONDON--Buried in a sleepy corner of the Harvard campus, somewhere in the nation's largest collection of psychological data, lies a slim folder whose sealed contents might help explain what drove the Unabomber to kill.

Theodore J. Kaczynski '62, who was arrested in 1996 after killing three and injuring 16 in a string of mail bombings spread over 20 years, participated in an intensive, sometimes brutal, three-year psychological study while a Harvard undergraduate.

The results of the study, directed by famed psychologist Henry A. Murray, are now housed at the Radcliffe Institute research center named in Murray's honor. But though the records may shed light on Kaczynski's psychological history, the Murray Center has locked the file up for good.

"We have a very strong policy of maintaining the confidentiality of people who participate in studies archived here," Murray Center Director Annemette Sorensen said. "This particular file has been permanently removed, with the reason being that we cannot protect its confidentiality anymore."

Kaczynski's code name in the study--"Lawful"--has become widely known to journalists and researchers, and Sorensen said that because the Murray Center promises to maintain the confidentiality of study participants, there are no circumstances under which Kaczynski's file could be opened.

"It would undermine everything we try to do here, and it would really mean that we would begin to lose control over those important principles," she said.

Author Alston Chase suggested in a recent Atlantic Monthly article that Kaczynski's participation in the Murray study might have pushed him over the edge from an isolated student to a revolutionary against science and society. Kaczynski's bomb attacks often targeted science professors and airline executives.

Called "Multiform Assessments of Personality Development Among Gifted College Men," the study consumed hundreds of hours of participants' time over three years.