I strongly suggest reading Judge Pérez-Giménez's Opinion and Order in U.S. v. Angel González-Méndez, 352 F.Supp.2d 173, 66 Fed. R. Evid. Serv. 301 (D.Puerto Rico January 14, 2005) concerning the Government's interest in inquiring as to the source of attorneys fees --pretrial-- in a case involving the robbery of a financial institution and in which none of the stolen funds have been recovered. Defendants apparently have no legitimate income either. Judge Pérez-Giménez tells the Government that they cannot use the procedure set forth for so-called "Nebbia hearings" (after US v. Nebbia, 357 F.2d 303 (2d Cir. 1966)) for this sort of pretrial investigation. However, and this is important, take a careful look at n. 3 of the opinion.