The weight of the case against the man charged with being the Unabomber would seem to be overwhelming.
Even before federal agents searched his remote Montana cabin, they had assembled detailed evidence that Theodore Kaczynski was responsible for a nearly 18-year spree of bombings that killed three and injured 23 others. The cabin itself yielded hundreds of pieces of further evidence, everything from bombmaking material to the original manuscript of the Unabomber's published antitechnology manifesto and the typewriter used to write it.
Despite this mountain of apparent proof, there is still ample room for Mr. Kaczynski's lawyers to mount a serious defense, experts say. In its bid to cast "reasonable doubt" on whether Kaczynski is indeed the Unabomber, they say, the defense will vigorously challenge the forensic evidence that forms much of the government's case.
Kaczynski pleaded innocent in federal court in Sacramento, Calif., on Tuesday to a 10-count federal indictment. He is charged with four separate bombings that killed two individuals in Sacramento and injured two others elsewhere. All four bombs were either placed in, mailed to, or mailed from Sacramento, the government says.
The likely line of defense will be to hammer away at the circumstantial nature of the evidence linking these bombs to the former University of California mathematics professor. So far, federal agents have failed to turn up an eyewitness who can concretely place Kaczynski at the actual scene of these acts.
"We have not seen any evidence yet which puts him at the place where he could either plant or mail the bombs," says San Francisco defense attorney Douglas Horngrad, who has represented numerous political activists. "They can't just say he had [bombmaking] material, therefore he bombs."
Mr. Horngrad successfully defended Earth First activists charged with transporting a bomb that exploded in their car six years ago in Oakland, Calif. "The FBI thought they had an overwhelming case," he points out. "Just because the FBI says so doesn't make it so."
The government will also have to provide a motive that links the widely disparate nature of the Unabomber's victims to Kaczynski. Federal investigators were themselves stymied in their effort to identify the elusive Unabomber by the absence of any apparent common theme linking the victims of the 16 different bombings.
"The defense could be that [Kaczynski] is a fanatic who has become obsessed with the Unabomber because his life seemed so closely in parallel with the person carrying out the bombings," suggests Joseph Russoniello, a former US Attorney in San Francisco.
But other experts contend that the sheer amount of evidence makes the government's case compelling. "In this kind of case, circumstantial evidence is perhaps better for prosecutors because it is less prone to mistakes by eyewitnesses," says attorney Jerrold Ladar, a former federal prosecutor.
This is likely to set up a prolonged examination by the defense team of the forensic evidence assembled by the government - a situation reminiscent of the murder trial of O.J. Simpson. "From what I've seen, this trial is going to be the forensic experts' full employment act," says Horngrad.
Kaczynski's second option is a psychiatric defense, experts add. Defense attorneys may argue that he is mentally disturbed and therefore couldn't, legally speaking, form intent to commit the crimes.
But insanity defenses are very limited under federal law since the attempt by John Hinckley Jr. to use such a defense in his attempted assassination of President Reagan, says former federal prosecutor John Gibbons. It is rarely used and even more rarely succeeds.
If the government decides to seek the death penalty, which many observers believe is likely, an insanity defense is even more problematic. If the defense tries to use the insanity plea during the "guilt phase" of the trial and fails, it would be hard-pressed to make the same arguments during the penalty phase when the jury would decide on the death penalty.
A third option is to carry out a political defense, suggests attorney Tony Serra, who defended accused bombers from the radical New World Liberation Front in the early 1980s. Kaczynski could argue he was acting to avert a greater harm to society through his actions, a defense based on the legal doctrines of imperfect self-defense and necessity, Mr. Serra says.
Federal defender Quin Devir, who is heading Kaczynski's defense, is an experienced trial attorney, having served for years as state public defender. "He is a very creative, very smart, very hard-working lawyer," says Horngrad.
The case is not likely to go to trial for at least a year.