BOULDER, Colo. (AP) _ Boulder County District Attorney Mary Lacy defended her decision to bring John Mark Karr back from Thailand to be investigated in the 1996 slaying of JonBenet Ramsey.

``The decisions were mine,'' Lacy said, one day after she dropped the case against the 41-year-old schoolteacher. ``I should be held accountable.''

Just as she began taking questions, a fire alarm disrupted the news conference, but it resumed a few minutes later.

Karr, a 41-year-old schoolteacher fascinated with JonBenet and Polly Klaas, a murdered California girl, said after his arrest in Thailand this month that he was with JonBenet at the time of her slaying, which he called an accident.

But DNA tests did not match Karr to material found on the girl's body. Prosecutors suggested in court papers that Karr was just a man with a twisted obsession who confessed to a crime he didn't commit.

The DNA mismatch between Karr and evidence in the Ramsey slaying was a setback for prosecutors, but they promised to continue searching for the six-year-old beauty queen's killer.

``This case is not closed,'' Lacy said before her news conference Tuesday.

JonBenet's aunt, Pamela Paugh, said that she wasn't terribly shocked to learn that Karr's public confession to being with JonBenet when she died didn't hold up.

``I think one of two things is going on: Either he is quite disturbed, and in that respect needs a lot of help and care, or he has perpetrated quite the fraud on the American public and the victims' families, and he needs help and a lot of care,'' Paugh told CBS' ``The Early Show.''

``For us, this isn't a story that ebbs and flows _ this is real life. So we have to maintain a certain amount of calmness through anything that happens. Otherwise you can be on a rollercoaster every week of your life.''

JonBenet's father found the little girl's body in the basement of their Boulder home on the day after Christmas 1996. For years, suspicion has focused on either an intruder or the girl's parents, John and Patsy Ramsey.

Prosecutors suggested in court papers that Karr was just a man with a twisted obsession who confessed to a crime he didn't commit. Karr had made graphic claims in a series of e-mails about JonBenet's killing, describing sexual acts with her, her death and writing at one point that he envisioned Johnny Depp playing him in a movie about how he killed JonBenet. He wrote that the movie would make $1 billion.

Karr was being held at the Boulder jail until he can be sent to Sonoma County, Calif., to face misdemeanor child pornography charges dating to 2001. An extradition hearing was scheduled for Tuesday afternoon.

Karr was never formally charged in the slaying. In court papers, Lacy defended the decision to arrest him and bring him back to the United States for further investigation, saying he might have otherwise fled and may have been targeting children in Thailand.

Lacy said Karr emerged as a suspect in April after he spent several years exchanging e-mails and 11 telephone calls with a University of Colorado journalism professor who had produced documentaries on the case.

The District Attorney's office released explicit details of statements Karr had made in those exchanges with professor Michael Tracey, who had alerted authorities. Karr told the professor he accidentally killed JonBenet during sex and tasted her blood after he injured her, prosecutors said.

``Are you asking me why I killed JonBenet? I don't see it that way,'' Karr wrote in a May 22 e-mail. ``Her and I were engaging in a romantic and very sexual interaction. It went bad and it was my fault.''

But the claims were lies, prosecutors said. The Denver crime lab conducted DNA tests Friday on a cheek swab taken from Karr and were unable to connect him to the crime.

``This information is critical because ... if Mr. 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,'' Lacy said in court papers.

She also said authorities found no evidence Karr was in Boulder at the time of the slaying. She said Karr's family provided ``strong circumstantial support'' for their belief that he was with them in Georgia, celebrating the holidays.

The backlash was swift. Defense attorney Seth Temin said Karr never should have been arrested. Republican Gov. Bill Owens said Lacy, a Democrat, ``should be held accountable for the most extravagant and expensive DNA test in Colorado history.''

At a Boulder coffee shop Tuesday, diner Dana Gomes said Lacy ``stuck her neck out further than she had to go.''

``They were poking at rain clouds hoping it was going to rain the truth,'' she said.

When Karr was arrested in Thailand, Ramsey family attorney Lin Wood pronounced it a vindication for JonBenet's parents. Patsy Ramsey died of cancer in June.

On Monday, the attorney said: ``From day one, John Ramsey publicly stated that he did not want the public or the media to jump to judgment. He did not want the public or the media to engage in speculation, that he wanted the justice system to take its course.''

Nate Karr, John Karr's brother, said he was elated his brother would not be charged. ``We're just going to be celebrating with family,'' he said.

But Scott Robinson, a Denver attorney who has followed the case from the beginning, said Karr may be charged with lying about his role.

``Seems to me there should be some criminal consequences,'' he said. ``He has cost the taxpayers an enormous amount of money.''

The district attorney defended the handling of the case, saying there was no way to take a cheek swab from Karr without alerting him that he was under investigation.

Also, Karr was about to start a teaching job in Thailand, and in his correspondence began to describe an interest in several girls ``in much the same terms that he had described his interest in JonBenet,'' Lacy said in court papers.

In a July 19 e-mail, Karr described feeling excited because two 5-year-olds were ``flashing their hot little bellybuttons at me'' and later said a ``naked little foot felt so sexy in my hand,'' prosecutors said. Karr's arrest was less than a month later.

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Associated Press writers Jon Sarche in Boulder, Dan Elliott, P. Solomon Banda and Sandy Shore in Denver, Harry R. Weber in Atlanta and Scott Lindlaw in San Francisco contributed to this report.

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On the Net:

D.A. filing: http://www.courts.state.co.us/docs/06CR1244MQUASH1.pdf