As has been repeated ad nauseam, this relates to the Federal charges of selling "fake Indian art" that were later thrown out. NP was charged in 2000 by the Feds. According to this Federal Bureau of Prisons website:
"It is possible that a record may exist for an individual who was in BOP custody but never served a federal sentence of incarceration. Here are some examples of when this might occur:
when someone was detained pre-trial but criminal charges were dismissedDING DING DING when someone was held as a material witness when someone was held for civil contempt