I remember watching former FBI profiler Candice DeLong over the weekend saying that the Fredricksburg VA murder was probably not related to the other murders (a short time before the cops confirmed that it was), and speculated about the age. She was not very helpful. In fact, I remember yelling at the screen, "you idiot."
Cops are very loathe to give out all information in a case while the case is still under active investigation. They may well have wanted to hold back on the Tarot card because it is one of those things only the killer would know. Now it's public knowledge. If the killer was going to use this as his signature--and the card holds significant clues, like his handwriting--that's long gone because now everyone knows about it. Do you have a need to have everything about the case known to the public (as well as the killer) in exchange for hampering the investigation, with the possibility of screwing up the case?
Now I'm thinking it's some wacked out teenager or young adult.
I think somebody really screwed up by leaking the Tarot information, but it could benefit the investigation because I don't think the killer is finished yet. Now that the Tarot card is public, depending on what kind of mentality it is we're dealing with, the next time (and I'm convinced there will be a next time) the killer might make a more flamboyant "statement". The more flamboyant he gets, the more chance for clues to be left behind and as the killer "acknowledges" the publicity, the more likely he'll be to start making real mistakes. If the killer is a teenager or young adult, the pressure of law enforcement chasing him will start to get to him sooner. A teenager or young adult will crack sooner than an older, more disciplined person.