The Long, Twisted Odyssey of John Mark Karr

Two months ago, you had never heard of a man named John Mark Karr.

Then, for just shy of two weeks, authorities considered Karr the chief suspect in the 1996 slaying of 6-year-old beauty queen JonBenet Ramsey.

Before millions of worldwide viewers, he said on cameras in Thailand, "I was with her when she died."

DNA evidence failed to link Karr to the killing.

After that case fell apart, he was still a curious character, retreating from the spotlight onto a side stage where he faced charges of child pornography possession from 2001.

Americans were no longer interested in his every move, but knew he was locked away somewhere, off the streets.

On Thursday, all that changed.

The pornography charges against Karr were dropped after investigators said they had lost pieces of evidence that were crucial to the case.

Neither his purported open sexual desire for children nor his history of marrying and allegedly abusing underage girls led to any charges that would hold up in court. As far as the justice system could tell, Karr was guilty of nothing more than being creepy.

He walked out of jail and into the world -- a different world than the one he had last seen.

Now, a little more than a month after his initial capture, Karr is a real and strange kind of celebrity.

A Cold Case Heats Up

Since the death of JonBenet on Christmas 1996, no one seemed more eager to see the crime solved than the people of Boulder, Colo.

In a community so small that everyone seemed to know someone who knew the Ramseys, Karr's alleged confession initially appeared to mean the end to a 10-year cold case that made Boulder famous for all the wrong reasons.

"Everyone felt really relieved," said Bill Wise, a former prosecutor in Boulder County who lead the investigation in its early stages. "At first they felt this must be the guy."

Investigators were so excited they largely pardoned the media circus that gathered around the court building and hotel bars of their city.

"At the beginning they thought it was worth -- let the media attention be there, as long as they've got the guy," Wise told ABC News.

But then, things didn't add up. Karr's family offered up an alibi, saying that he was home with his family that Christmas. Karr couldn't be placed anywhere in the state of Colorado, much less anywhere near the crime scene.

In Boulder, there were growing suspicions that Karr had nothing to do with the crime and that District Attorney Mary Lacy's case against him was only as strong as his shaky confession.

Even though picking Karr up and keeping him in custody might have been the logical move -- he was considered a clear flight risk with a tendency to work near young children -- it didn't make Karr JonBenet's killer.

Then the other shoe dropped with a thud.

Karr's DNA tests were returned, and he didn't match evidence lifted off JonBenet's body.

Anyone who still needed convincing got the proof they needed. Karr was not JonBenet's killer.

"Everybody felt bad," Wise said. "They wanted a solution to that case."

'He Must Be Teflon'

Karr was elated about the collapse of the pornography case and overjoyed to be a free man again.

His lawyers told ABC News "he was elated and surprised and a little disbelieving at first. … But his overwhelming emotion was happiness."

Not everyone is as happy.

Karr is not charged with any crime and not required to register as a sex offender.

"Now they have absolutely nothing to keep an eye on this guy," said California criminal defense lawyer Kevin McDermott. "No reporting requirements. No monitoring requirements whatsoever."

"He must be Teflon," McDermott said.

At the heart of Karr's freedom is a piece of lost hardware -- the computer he allegedly used to possess sexual images of children.

That computer, which served as both evidence and a crime scene, was nowhere to be found. It was lost by investigators when they moved from one storage facility to another in 2002.

"I'm not that surprised that evidence would get lost or disappear. … It's been sitting there for five years" said McDermott, who has worked on sex crimes.

Karr has only the botched evidence to thank for his freedom.

Possession of child pornography in California is a misdemeanor for first-time offenders, which means they can easily escape charges by simply moving to another state.

"That's how guys like this get away," McDermott said. "They get slapped on the wrist, and then they get smarter about how they go about offending."

A solution to this legal loophole, McDermott believes, might be to make child pornography possession a felony no matter what, even if it's a first offense.

But in the interim, the former prosecutor and father of two will simply try doubly hard to keep his children away from wandering predators.

"There's just no accounting for people like this. All you can do is make sure your kids don't fall into this trap," he said.

"You have to teach your kids to be aware that people like that are out there -- as tough as it seems that you have to limit how friendly you are."

A Failure of Justice?

Dropping a case because of lost evidence may seem like a failure of the justice system, an accident that let a probable pedophile and possible molester go free.

But perhaps the greater failure of justice is that it has failed JonBenet: Ten years after her death, there are no leads in sight.

The crime scene has been scrubbed clean as the Ramsey home was bought and sold by new owners.

"I don't think it's ever it's going to be solved," said former prosecutor Wise.

"If you don't have a DNA match after 10 years, I think [chances are] really thin," he said.

The best hope for the people of Boulder -- and, of course, for JonBenet -- is that someone will step forward to confess and that this time, it will be for real.