You don't need to know where the proceeds came from, only that they're proceeds of specified unlawful activity.
To obtain a conviction
under 1957, the government must prove that the defendant
knowingly engaged, or attempted to engage, in a monetary
transaction involving criminally derived property, in excess of
$10,000, derived from specified criminal activity. 18 U.S.C.
1957(a). The statute defines "monetary transaction" as "the
deposit, withdrawal, transfer, or exchange, in or affecting
interstate or foreign commerce, of funds or a monetary instrument
. . . by, through, or to a financial institution . . . including
any transaction that would be a financial transaction under section
1956(c)(4)(B)" 18 U.S.C. 1957(f)(1). The statute requires that
the monetary transaction involve money "derived from" or "obtained
from" a criminal offense. See 18 U.S.C. 1957(f)(2) (defining
"criminally derived property" as "any property constituting, or
derived from, proceeds obtained from a criminal offense"). Thus,
in order for a defendant to violate this statute, the funds in
question must already be "proceeds obtained from a criminal
offense" when the defendant transfers them. See United States v.
Johnson, 971 F.2d 562, 568-69 (10th Cir. 1992) (examining plain
language and legislative history of 1957 and holding that
proceeds must be criminally obtained prior to the transaction that
forms the basis for the 1957 money laundering conviction);
