Sacramento - The trial begins today of the alleged Unabomber, Mr Theodore Kaczynski, a man prosecutors say is one of the wiliest terrorists ever to wreak mayhem in the US. The defence lawyers will argue that the accused man is too mentally unstable to be held accountable for his actions. Mr Kaczynski (55) has pleaded not guilty to a single broad charge encompassing bomb attacks that killed a computer store owner and a timber industry lobbyist in Sacramento and maimed two college professors.