BOULDER, Colo. -- Cynthia Nye doesn't stock true crime books at the High Crimes Mystery Bookshop she runs on Boulder's Pearl Street Mall. Not even books about JonBenet Ramsey's 1996 murder, the hometown mystery that won't go away.

Nye said her customers just don't consider a real-life tragedy entertainment.

"It's easy to read about a fictional person being killed, or a mystery serial killer, because you know the bad guy is going to get his justice," she said. "There is so little resolution in real life."

For 10 years, that has been the case in the slaying of 6-year-old JonBenet, found strangled and bludgeoned in the basement of her family's home on the day after Christmas 1996.

With one-time suspect John Mark Karr unmasked as a fraud and the national media gone from Boulder, investigators are left again without a prime suspect and their ears ringing with criticism of the case's latest twists and turns.

District Attorney Mary Lacy conceded she has no hidden trump card to confirm the claims of any other would-be confessor simply because case details authorities normally keep secret has been fodder for books, news reports and Internet chatter over the years.

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

Like a mystery novel from Nye's downtown store, the puzzle pieces may be there, experts say. But like true crime stories, there is no guarantee they will fit together.

Max Houck, director of West Virginia University's Forensic Science Research Center and co-founder of the Institute for Cold Case Evaluation, said it's hard to imagine working a case so public that authorities can't eliminate confessors by holding back some details.

"If you, as an investigator, know something that only the killer would know, you have a hole card," he said. "But we're in an era where more and more is known about any public case that happens to hit the public's imagination, or at least the media's examination."

Houck could name few cases so scrutinized that every detail was out there: the Kennedy assassination, the Rosenberg spy case, the Lindbergh baby kidnapping.

Lacy, through a spokeswoman, declined an interview request. But in a news conference, she said she relied solely on phone calls and hundreds of pages of e-mails Karr swapped with University of Colorado journalism professor Michael Tracey to make the case for arresting Karr in Thailand last month and bringing him to Colorado. She admitted that her office acted on Karr's word alone, without any actual evidence.

Karr was Tracey's second "prime suspect" to be brought to the public eye. The first one, mentioned in a documentary Tracey produced several years ago, also turned out not to have even been in Boulder at the time of the slaying.

Karr, a 41-year-old former teacher, gave graphic accounts of the crime scene, detailed enough to convince the D.A.'s office he was for real. Plus, he gave personal details that authorities were able to confirm, suggesting he might be telling the truth. The case collapsed when his DNA failed to match evidence from the crime scene and relatives said he was with them in Alabama when JonBent was killed.

Richard Lavinthal, a former Justice Department spokesman and a public relations consultant for the legal field, criticized Lacy for admitting there was nothing left to separate suspects from pretenders.

"What District Attorney Lacy did was, in effect, announce to the world she has now made the case impossible to solve, unless through some fortuitous action there is someone out there who gets arrested and his DNA gets into a data bank and ends up matching the DNA from the case," Lavinthal said. "It's as if she put up a giant billboard that says 'Attention, the Ramsey case can never be solved.'"

And arresting Karr could hurt the investigation, said William Fleisher, a founder of a cold case investigative association called the Vidocq Society.

"It would be awful hard (to solve) unless the actual perpetrator came forth, bares his soul and provides real, corroborative evidence," he said.

The case remains an ugly chapter for the wealthy university town, as much a part city's lore as it's famed liberalism and scenic beauty. Never mind the atmosphere the city cultivates, from street musicians dotting a pedestrian mall to classical music piped into a spotless public restroom; JonBenet is what many think of when they think of Boulder.

Expressing frustration with the media and that seemingly endless association of JonBenet and Boulder, a motorist driving past reporters over the past week yelled: "Go home! You're not wanted here!"

Still, public fascination with the case is easy to understand, said Michael Radelet, a criminologist and chairman of the University of Colorado's sociology department.

The Ramsey family never fit in around here and some were eager to blame the girl's family, criticizing her role in beauty pageants and even the family's conservative politics, he said.

People who don't fit in with the power structure in any society often become targets, Radelet said, pointing to how white society often blamed blacks for crimes in the rural South decades ago.

Society is sometimes eager to pin crimes on the easiest targets.

"John Karr was an easy target. The guy is ... a loner," Radelet said. "Patsy Ramsey is a type of easy target. She's new rich, an outsider from Atlanta, Republican and a beauty queen. In Boulder, that's the same as being poor, uneducated and black in Birmingham in 1930 ... In that sense, John Karr and Patsy Ramsey are two sides of the same coin."

Radelet is a member of Families of Homicide Victims & Missing Persons, a group dedicated to solving some of the 1,200 unsolved homicides on the Colorado books. He said he would like JonBenet's killer to be found, but hopes the Karr episode will encourage investigators to focus on solving other crimes.

No chance. Lacy said she would press on in the JonBenet case.

Houck said the challenge is for investigators to keep arranging the pieces until they fit. Technology is evolving, and sometimes items that seem unconnected fit into a pattern.

Lou Smit, a renowned cold case investigator who has worked on the Ramsey case, won't talk specifically about it any more. But he said he remains a believer "that any cold case can be solved."