After DNA testing failed to link John Mark Karr to JonBenet Ramsey's murder this week, many might wonder: Why would somebody confess to a crime they didn't commit?
Experts say, while still fairly unusual, it does happen and there are two basic reasons why: the first is fame and the second, more frequent reason, is police coercion.
"In high-profile cases, one common reason is that some people have this pathological need for attention or recognition, a desire to get their names in the newspaper," says Saul Kassin, a psychology professor at John Jay College of Criminal Justice in New York and an expert in confessions. "And this may be one of those types of cases."
Indeed, Mr. Karr, who was arrested in Bangkok, Thailand, earlier this month, appeared to enjoy the attention he was getting from all the publicity.
Six-year-old JonBenet Ramsey, a child beauty queen, was found bludgeoned to death in the basement of her Boulder, Colo., home the day after Christmas in 1996. While speculation has centered on the family for years, Karr was not the first to confess to her murder.
There have been plenty of others throughout the years who linked themselves to high-profile murders, like Ramsey's, for that same reason.
"There is a need that many of us have to be the best of the best, whether the best doctor, the best writer, or in this case, the best killer," says Ray Hays, an associate professor of psychiatry at Baylor College of Medicine in Houston. "People want to be famous, even if that means being infamous."
For instance, the 1932 kidnapping and killing of aviator Charles Lindbergh's baby led more than 200 people to falsely confess – while the man ultimately convicted of the crime, Bruno Hauptmann, maintained his innocence to his execution.
And some 500 people throughout the years have confessed to killing 22-year-old actress Elizabeth Short in 1947, known as Hollywood's "Black Dahlia" murder.
During the 1980s, Texas prisoner Henry Lee Lucas bragged about killing up to 600 people, including Teamsters boss Jimmy Hoffa. He reportedly loved the notoriety he gained from his confessions, and was given extra prison perks for doing so.
"The fact is, it's boring to be in prison," says Dr. Hays, who followed the Lucas case.
But others who admit falsely to a crime may be delusional or have some other psychological disorder, experts say. Some may have guilt over a real crime they committed or may be protecting another family member, such as a teenager confessing to protect a parent. Others may become so immersed in a case that they have confused reality with fantasy.
Karr, for example, had been studying the Ramsey case for years, writing letters of apology to the family, and corresponding with a professor who had done several documentaries on the crime.
"He was obsessed with the case," says James Alan Fox, a professor of criminal justice at Northeastern University in Boston. "But the day after his arrest, it became clear that this guy had a lot of holes in his story."
For instance, Karr allegedly couldn't say how he knew the Ramseys, he called JonBenet's death an accident when evidence showed it was clearly not accidental, and he claimed to have had sex with her, though no semen was found on her body. Karr's family also said he was with them in either Georgia or Alabama that Christmas.
But many confession experts and psychologists are waiting to pass judgment on Karr's confession until more details about his interrogation come to light.
The most common reason for a false confession is police coercing a suspect into admitting to a crime with a long, threatening interrogation or promises of reduced sentences, experts say.
"For someone who's under stress, feels trapped, and wants out, confessing becomes almost a rational response," says Dr. Kassin. "People become very short-sighted and want to terminate that stress by any means possible."
False police-induced confessions have led almost 10 states in recent years to pass laws regarding the mandatory videotaping of the entire police interrogation process, not just the confession.
But that reform has been slow in coming and much more is needed, says Kassin.
"The problems we see in this area are just the tip of the iceberg," he says. "They continue to plague the system and, unlike the Karr case, police and prosecutors don't tend to drop those cases."