Regardless of whether Karr's confession is true or false, he has done more to educate the public about the problem of false confessions than even the Central Park Jogger Five did. Of course, there is a potential downside to all this coverage. The public might get the wrong impression that only the mentally ill or unbalanced would ever confess to crimes they did not commit. Thankfully, most of the real experts who have been quoted have made sure to remind the public that most false confessions are the product of coercive police interrogation techniques.
It's been fun watching all the coverage of the so-called confession of John Mark Karr, especially the forensic psychiatrists and psychologists spewing psychobabble about a man they have never clinically interviewed. John Mark Karr may be have a "sexual identity disorder" or any of the numerous diagnoses I've seen bandied about but IMHO it is bordering on malpractice to base such diagnoses on newspaper reports.
Bottom line is that it is too early to tell whether or not Karr's confession is voluntary or involuntary or true or false and anybody who says so either way is simply speculating. At this point, it's not even clear he confessed. His "I was with her when she died" and "her death was an accident" is at best an admission that he was present at the crime scene, far from a full confession chock full of details that only the true perpetrator would have known. While the bizarre press conference suggests the confession was "voluntary" and has led many to conclude that Karr is simply seeking attention (a fact strengthened by recent claims he is seeking a book or t.v. deal to defray legal expenses and pay for his kids' college costs), there are also some signs that his confession may have been shaped by police interrogation tactics -- the "accident scenario" is a classic police tactic of minimization, an effort to get a suspect to confess to a less heinous version of a crime, and statements by investigators that Karr confessed to committing only second degree murder smack of police suggestion. Best to wait until we hear more about the police investigation leading to Karr's detention in Thailand and to let the investigation take its course here and not to jump to any conclusions about Karr or the reliability of his confession.
What the media should be covering is what police will need to do to prove that Karr's confession is reliable. Police are trained to hold back details of the crime from the press and the public as a check against false confessors. If such facts exist (and they may have been leaked due to extensive press coverage), police will want to know if Karr has provided any such facts to authorities in Thailand or on the plane ride home. They will want to see if Karr can lead them to facts they did not know (evidence from the crime, perhaps a keepsake that proves he was in the Ramsey home, receipts showing he traveled to Colorado). They'll need to look for evidence of motive, means, and opportunity (a biggie here given that there is no evidence he knew the Ramseys, had access to their home, or even had a way to get to Colorado from Alabama over the holidays). And they will assess the "fit" between what Karr told them and the objectively knowable facts of the crime -- were there errors in Karr's statements?, are the facts he got right the kind that are not likely to be guessed correctly by chance?, etc. If Karr does seem to possess intimate knowledge of the crime, given the reams of information available about the case from public sources, many of which were apparently read by Karr, the real tough job for police and the media here is to make sure that Karr's apparent knowledge of key facts did not come from publicly available sources. Stay tuned.