The most important evidence amounts to this: DNA taken from two blood stains, hair and fibers taken from the body, half a footprint and two partial palm prints.

What it boils down to is this: It is infinitely easier to prove itinerant teacher John Mark Karr did not kill JonBenet Ramsey 10 years ago than it is to show beyond a shadow of a doubt that he garroted and beat the 6-year-old child he claims to have loved.

Because of the nature of DNA testing, it is simpler to prove a negative.

"DNA is the sure way to eliminate him," said Scott Robinson, a Denver defense attorney who has closely followed the case. "If it's negative, you ride that horse all the way to the stable."

The stable, in this case, being the exoneration of John Mark Karr, arrested in Bangkok last week and paraded before journalists to whom he professed his love for the little beauty pageant contestant and then claimed he was present when she died.

He called her death "an accident."

Since then, his fantastic professions have been met with increasing suspicion and distrust.

So if genetic testing rules him out, as some legal experts predict, what happens next?

"If it's not this man's DNA, then there has to be some very strong and compelling evidence that places him at the crime scene," said Lin Wood, the Ramsey family's longtime attorney. "Unless you have some positive evidence of DNA, it would be an extremely difficult case."

Difficult, agreed Robinson, but not impossible.

"There are other things," he said, including questions that Boulder District Attorney Mary Lacy should be asking: "Can we place him in Boulder at the time of the murder? Can we place him in some relationship with the Ramseys?"

Whether the prosecutor has the answers to those queries is anyone's guess at this point. Since announcing Karr's arrest, she has refused to comment on nearly all aspects of the investigation.

There is no publicly known evidence putting Karr in Boulder or any other town in Colorado. JonBenet's father, John Ramsey, has said he has no recollection of the man meeting anyone in his family.

Prosecutors would also have to corroborate Karr's statements to Thai police, including claims he sexually assaulted the girl, said Bob Grant, a former Adams County DA who helped investigate JonBenet's death.

An autopsy found no semen in or on the child's body, but noted vaginal abrasions and tearing of the hymen. There was not enough evidence to determine what caused those injuries.

The theory that an intruder killed JonBenet is supported by unexplained evidence: a mysterious boot print found outside the house after her body was found Dec. 26, 1996; marks on her body some say could have been made by a stun gun; and signs that someone may have entered the house through a basement window.

Then there is the DNA of an unknown male found in blood in JonBenet's underpants. Tests in 1997 and 1999 indicated it was from a male who was not a member of the Ramsey family.

Two years ago, Wood said a better-quality DNA profile was worked up but it did not match any samples in an FBI database of convicted violent offenders. At the time, that database included 1.5 million samples.

Celebrity forensic scientist Dr. Henry Lee, who initially participated in the Ramsey case, said even a positive DNA match is not always enough to convict.

"It can never be 100 percent," he said of the analysis which matches samples and donors by statistical probability.

If it turns out that a DNA sample from Karr matches crime-scene DNA, the first salvo from his attorney — whomever that turns out to be — would be against the testing process. As demonstrated by the O.J. Simpson criminal case, even supposedly ironclad genetic test results can be shaken by lapses in testing protocols or procedural breakdowns in handling evidence.

"Whoever represents this guy will whine about the testing that was done, and not being able to do their own testing," Grant said. "It's pretty standard."

There were also DNA traces found under the child's fingernails, but they were degraded and tests were inconclusive, Grant said.

Prosecutors need to find out if Karr truly knows anything about the case that isn't public knowledge, he said. In this sensationalized investigation, he does not think that is possible.

"The whole world knows everything about this case," Grant said. "I'd be surprised if everything I knew (as an investigator) wasn't out in the public domain."