I don’t know which level/branch of LE arrested Epstein. Hopefully others chime in.
Concerning charges for Epstein...Federal charges, Federal Prosecutor:
“Billionaire convicted sex offender Jeffrey Epstein was arrested Saturday in connection with federal sex trafficking allegations, law enforcement officials said...
The arrest was part of a joint NYPD and FBI investigation...
Multiple people briefed on the matter say that the U.S. Attorney’s Office for the Southern District of New York’s public corruption unit is prosecuting the case.”