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The prosecutor in the JonBenet Ramsey case Tuesday defended her decision to bring John Mark Karr halfway around the world to Colorado for investigation, saying it was difficult to separate fact from fantasy in his lurid account because every detail of the six-year-old girl's slaying is public knowledge.

District Attorney Mary Lacy said that in addition to Karr's graphic account, his obvious predilection for little girls forced her hand.

"We felt we could not ignore this. We had to follow it," she said. "There was a real public safety concern here directed at a particular child" in Thailand, and a forensic psychologist said Karr "was dangerous, this person was escalating."

• Timeline: The JonBenet Ramsey Murder Investigation

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In the day since Lacy's office announced it was dropping the case against Karr, the district attorney has been bitterly criticized by defense attorneys and by Governor Bill Owens, who accused her of wasting thousands of dollars on the "most expensive DNA test in Colorado history."

For 90 minutes, Lacy patiently explained why authorities spent at least $9,300 to bring Karr back from Thailand after he balked at a more sophisticated DNA test that could have ruled him out as a suspect in the 1996 slaying of the 6-year-old beauty queen at her Boulder home.

Lacy said she wanted the investigation done quietly, but details leaked to the media.

She said her office has checked out some 200 suspects over the years and dealt with "dozens" of false confessions. The problem, she said, is that there is nothing left that only the killer would know.

"As far as we can tell, there is no physical evidence in this case that has not been in the public domain," Lacy said. "The ability of our office or any law enforcement to connect this kind of a person — based on something they know about it that no one else knows — was gone a long time ago."

Lacy said she has received calls from people calling for her to be "tarred and feathered" and "run out of town."

"The decisions were mine," said Lacy, who will be forced out by term limits in 2008. "The responsibility is mine, and I should be held accountable for all decisions in this case."

Karr is being held at the Boulder jail until he can be sent to Sonoma County, California, to face five child pornography charges dating to 2001. An extradition hearing was scheduled in Boulder for Tuesday afternoon. If convicted, Karr could get a year in prison on each count.

Karr's father and brother, Wexford and Nate Karr, were at the Boulder jail on Tuesday, but left without commenting.

Karr spent years corresponding by e-mail and talking by phone with a Colorado journalism professor, who tipped off authorities. Karr claimed that he accidentally killed JonBenet during a ritualistic sexual encounter.

His claims included personal details investigators were able to verify, including the fact that his mother tried to burn him when he was a child, Lacy said.

That suggested he might be telling the truth about being a killer, even though his references to everything from JonBenet's bracelet and runny nose to her bludgeoned skull can be easily found in books or on the Web, prosecutors said.

"This guy confessed on numerous occasions in great detail," said Peter Maguire, a deputy district attorney. "He confessed in e-mails, he confessed in telephone conversations. ... He admitted it to a police officer. This was a bizarre crime and the person who committed this crime acted in a bizarre way."

Ultimately, DNA tests on blood in JonBenet's underwear failed to connect Karr to the crime, and investigators had no evidence he was even in Boulder at the time.

Prosecutors said they have received fresh tips since they arrested Karr, but none seem promising.

Lacy said she was frustrated as the 10-year anniversary of the slaying approaches. "I don't think there's anyone who doesn't want to solve this crime with the right person," she said. "We still very much hope that it will be solved at some point."

As for Karr, Lacy said she will cooperate with authorities in Sonoma County, California, "to get him convicted, registered, treated and supervised."

"I also know that at least every parent in this country has seen his picture and knows his name so you have some ability to protect yourself against him," Lacy said.