I understood that this sleazy guy, John Mark Karr, was under indictment for child pornography in California, then he fled the country rather than appear in court. And he hasn't returned to the USA until now.
If his confession to murdering JonBonet Ramsey is a hoax, he should face the charges against him in California, adding the charges that he skipped bond.
This guy needs to be put in a U.S. prison and NOT returned to any other country, where he could continue to teach school and come in contact with children.
I think him being a whack job is a given. I also would bet he was capable of the crime. Did he do it? That's a different question. They have DNA from under her fingernails. If there's a match, you can put him away. If not, he's still dangerous, and should not see the light of day again.