Anthony Martin, a blogger at Examiner.com, does some digging and turns up an interesting connection. Martin did some digging into James Eric Fuller, the victim of the Tucson shooting who threatened the Arizona Tea Party founder at town hall meeting filmed by ABC news.
According to Arizona courthouse records, someone named Prince Eric Fuller changed their name to James Eric Fuller in 1997.
In 1974, the Supreme Court heard the case of Prince Eric Fuller v. State of Oregon regarding whether an destitute criminal could be forced to pay the court costs associated with their conviction. It seems that he was convicted of a Sodomy in the third degree, a Class D felony.
Third-degree sodomy usually involves sexual intercourse without consent or with someone incapable of giving consent, e.g. someone who is mentally incapacitated or underage.
It's possible that this is a different Prince Eric Fuller, but the name does not seem that common.
Since his threat, Fuller has apologized for his outburst through his girlfriend. He is under psychatric care.