I believe they're referring to the specific condition of JB's body as a result of the crime, such as would be included in a medical examiner's report. Which I also believe was out on the web a few years back.
This is a case that has been talked about to the nth degree on TV, radio and in print from the beginning. Someone obsessed with the case could easily come across obscure details that are accessible to the public, but not widely known. Someone obsessed with the case could easily take those obscure details and surmise other details that might come close to the truth, or even be the truth.
That's precisely what people do when they research and write books about murder cases.
http://www.thesmokinggun.com/archive/jonbenet1.html
Autopsy documents here.... FWIW
I also read something about a reference to "SBCT" on the ransom note. Supposedly, Karr wrote the same reference in his yearbook several years before the killing. Give them a few weeks, and we should know a lot more whether this is for real or not.