The trial is underway in California of Theodore Kaczynski, the man prosecutors believe was responsible for a series of bombings around the United States over the last two decades which killed three people and maimed dozens of others. The author of the mysterious and apparently random attacks became famous as the Unabomber, a name invented by FBI investigators who spent thousands of hours trying to track him down. Mr Kaczynski's family has been angered by the US government's refusal to accept his plea of guilty in return for being spared the death penalty. Our US Affairs analyst, Maurice Walsh, reports.

Throughout the 1980s and early 1990s the deeds of the Unabomber occupied a special place in the American imagination. Every so often somebody would be killed by a package bomb or a device left outside an office.

There was little to connect the bombs besides the fact that they were directed at universities, airlines and scientists. The FBI spent years building up a profile of a lone bomb maker whose motivation appeared to be disgust with modern technology.

Three years ago two newspapers published an anti-technological tract sent to them by the Unabomber. After reading it David Kaczynski went to the FBI and told them his brother - a Harvard-educated mathematician living alone in a tiny cabin in the mountains of Montana - might be the man they were looking for.

Now, Ted Kaczynski is accused of killing a computer salesman and a lobbyist for the forestry business. He has refused to allow his lawyers to enter an insanity plea.

But he did offer to plead guilty if he could escape the death penalty. The government's refusal to accept this has dismayed Mr Kaczynski's brother David.