I've been wondering about this. I know that, say, it is generally a crime to file a false police report, and the motivation for this seems logical because that it wastes police time and resources - and thus takes them away from being able to spend them on real leads, and thus also to degrade the public safety by that little bit.
But I also know that, if one admits to making a crime on a public forum, such as an Internet forum, it is possible that a prosecutor who is looking at such fora could potentially use the admission to bring charges, even if the admission is not specifically directed toward one. However, what I wonder about is if some of the above logic does not also, then, apply to a situation like this: if one were to, given this fact, falsely announce on such a forum that one had committed a crime that one actually did not, could it amount to having the same effect of wasting prosecutor/law enforcement time albeit in a more indirect way that sneaks through their attitudes, and thus potentially also be considered some kind of crime?
(I want to point out I'm not referring to making a false claim to be the perpetrator of a known crime, or to falsely claim someone else is that perpetrator to, say, get reward money. I'm referring specifically to announcing an unknown crime one did not commit, a crime that does not exist, on a public venue like a forum that is not specifically a channel to police or other authorities. If a prosecutor got ahold of it and tried to pursue it, and it were during the course of that proven a hoax, what would happen?)
FWIW, the country in question is the United States.