There are new questions about bitcoin, following the arrests of two men on charges they laundered money using the virtual currency. One of the arrests took place at JFK Airport.
The charges come just as New York State begins two days of hearings, aimed at bringing transparency to bitcoin transactions.
The Department of Financial Services is considering requiring a license to trade in bitcoin.
The first witnesses scheduled to appear on Tuesday include Cameron and Tyler Winklevoss, the twins memorably portrayed in the movie "The Social Network."
They will probably face some uncomfortable questions. Charlie Schrem, the man arrested at JFK on Sunday, was the CEO of a bitcoin company in which they invested.
The arrests are connected with a spectacular bust last year, of a website called Silk Road.
Authorities say Silk Road was a marketplace for illicit drugs. More than a billion dollars of trade took place there, and it was largely anonymous, because Silk Road used bitcoin.