BROTHER SPEAKS OUT TO HELP BOMB SUSPECT.

Byline: David Johnston and Janny Scott The New York Times

Breaking his public silence, David Kaczynski described in an interview how he had reluctantly come to the ``horrible'' realization that his older brother, Theodore, could be the Unabomber. He recounted his anguished decision to turn him in to prevent more lives from being lost, and he pleaded that his brother, if convicted in the fatal bomb attacks, be spared the death penalty.

Over six hours on Tuesday, David Kaczynski recalled how, at first, he had resisted his wife's suggestions last summer that Ted Kaczynski might be the Unabomber. When she prodded him to read the Unabomber's 35,000-word manifesto on the Internet, he sat, in shock, before a glowing computer screen in the library of the upstate New York college where his wife taught.

Dismay turned to anger, David Kaczynski said, when he and his wife, Linda Patrik, realized they might have unwittingly helped finance two of the Unabomber's deadly attacks by agreeing to requests Ted Kaczynski made for money, $1,000 in 1994 and $2,000 in 1995, each about two months before a bombing. ``It was really chilling,'' David Kaczynski said.

In the interview, accompanied by his lawyer, Anthony P. Bisceglie, Kaczynski would not say whether he believes his brother is guilty. But he said that his belief that he had acted properly had been confirmed by events since February, when he provided Ted Kaczynski's identity to the government with the help of Bisceglie, a corporate and white-collar trial lawyer in Washington, D.C.

Even so, David Kaczynski said, he was speaking out now in the hope that a fuller understanding of his brother would humanize a figure who he said had been erroneously depicted in some accounts as an evil genius who had lashed out at the technological world he abhorred.

And, he said, by agreeing to talk now, he might help save his brother's life later in a case in which the death penalty could be imposed.

``Clearly, part of my whole involvement in coming forward in this whole thing was a respect for life, that human life is really valuable, that certainly Ted did not in my mind have adequate justification,'' David Kaczynski said. ``If he did attack people and kill people, that was wrong. But by the same token, I feel it would be very wrong if he were killed in the name of some notion or principle of justice. I think it's important that people see him as a human being.''

So far, Ted Kaczynski, a Harvard-trained mathematician who was arrested on April 3, has not been charged with any Unabomber crimes. He is being held in a Montana jail on federal charges of possessing explosive components. But based on the trove of evidence discovered in Kaczynski's mountain cabin, law-enforcement officials said, federal prosecutors are preparing to charge him in the nearly 18-year string of package bombings, which killed 3 people and injured 23 others.

In the interview, conducted in a 45th-floor hotel suite with a sweeping view of midtown Manhattan, David Kaczynski said he had been closer than anyone to his brother until Ted Kaczynski angrily spurned him in 1989 for deciding to get married.

David Kaczynski, a 46-year-old social worker from Schenectady, N.Y., who works in a shelter for runaways, sought to keep the interview focused on his brother rather than himself. He also declined to be photographed.

Thoughtfully, and at times emotionally, Kaczynski detailed the life history of his 54-year-old brother and cast new light on the suspect's personality, mental problems and troubled relationships, on the evolution of his ideas, and even on the sources of money that allowed him to travel around the country.