BOULDER, Colo. – The man who convinced Colorado prosecutors he might be JonBenet Ramsey’s killer was unmasked as a liar Monday after his DNA failed to match genetic material on the slain 6-year-old’s body.

John Mark Karr claimed he “accidentally” killed his “little princess” a decade ago while engaged in a sex act that involved strangulation and “tasting her blood.” The evidence said otherwise.

“Because his DNA does not match that found in the victim’s blood in her underwear, the People would not be able to establish that Mr. Karr committed this crime despite his repeated insistence that he did,” Boulder District Attorney Mary Lacy wrote in a motion to quash Karr’s arrest warrant.

In addition, Lacy wrote, Karr’s kin provided “strong circumstantial support” for their belief that he was celebrating Christmas with them in Georgia when JonBenet was killed in Boulder.

Saying, “This case is not closed,” Lacy vowed “to continue to investigate leads and pursue justice.”

Karr spent the night in the Boulder County Jail and was today to determine whether he will be extradited to California on unrelated misdemeanor child pornography charges.

Lacy’s predecessor took heat for botching the initial investigation into the horrific murder that riveted the nation when JonBenet was found strangled in the basement of her family home on Dec. 26, 1996.

Monday night, Lacy was criticized for letting Karr go after spending thousands of taxpayer dollars on a first-class flight from Thailand and a chartered jet from California to Boulder.

“I find it incredible that Boulder authorities wasted thousands of taxpayer dollars to bring Karr to Colorado given such a lack of evidence,” Gov. Bill Owens said. “Mary Lacy should be held accountable for the most extravagant and expensive DNA test in Colorado history.”

Boulder Public Defender Seth Temin said Lacy never had a case against Karr.

“They took this man and dragged him here from Bangkok, Thailand, with no forensic evidence confirming the allegations against him and no independent factors leading to a presumption he did anything wrong,” Temin said.

Karr’s arrest 12 days ago briefly dispelled the cloud of suspicion that had been hanging over JonBenet’s parents, John and Patsy Ramsey. Patsy Ramsey died of ovarian cancer this year.

“For me it’s never been a question of John and Patsy being under that stupid umbrella (of suspicion),” Patsy Ramsey’s sister Pam Paugh said.

Karr, a 41-year-old former schoolteacher from Alabama who had been on the run for five years, was nabbed a dozen days ago as he was prepping for a sex-change operation.

In a bizarre public confession, Karr claimed he was with JonBenet when she was killed and answered “no” when asked if he was innocent.

‘Best friend’

But the motion to quash Karr’s arrest warrant revealed that Karr was playing with prosecutors – and the Colorado journalism professor he exchanged e-mails with – for much longer.

Karr began corresponding with his “best friend,” professor Michael Tracey – and signing his missives as “D” and “Daxis” – in 2002.

At first, Karr appeared to be obsessed with the JonBenet crime. Then in April, Karr “claimed to know two people who participated in the crime,” the motion states. “He later admitted personal responsibility for the death.”

“It is not important that ANYONE understands,” Karr wrote in an e-mail. “It is only important that it is revealed.”

Karr kept his name and whereabouts secret, but told Tracey he fled the U.S. “because he had been investigated in connection with the abduction and/or murder of other young children,” according to the motion.

Karr also asked Tracey to forward a note to John and Patsy Ramsey “so that he could explain his relationship to their daughter and her death.”

“Tell them I loved JonBenet so much,” Karr wrote in one e-mail.

Unbeknown to Karr, Tracey was already in touch with prosecutors and they were trying to trace the suspect’s e-mails and telephone calls.

Meanwhile, Karr claimed he had been “involved romantically and sexually with a number of young girls and expressed a preference for girls about 6 years of age.”

After Patsy Ramsey died, Karr “began to express sexual interest in specific young girls” at the Thai school where he was about to start teaching.

At that point, detectives managed to track Karr down. Fearing he might flee, they arrested him to get his DNA.

“This information is critical,” Lacy said in the motion. “If Karr’s account of his sexual involvement with the victim were accurate, it would have been highly likely that his saliva would have been mixed with the blood in the underwear.”

But after testing Karr’s sample, investigators determined that he “was not the source of the DNA found in the underwear of JonBenet Ramsey.”

Still unanswered was the question that has perplexed prosecutors for a decade: Who killed JonBenet?