Oh. Because the banks are cooperating and providing banking records. Unraveling financial trails is a well known skill for Senators, and a piece of cake these days - Senators are powerful, they can see a lot of things. If you go to your local welfare office they can pull up your banking records, and the banks have you 40 years back - so you can imagine what Senators can see. If you spent 20 grand in a hotel in Hong Kong they'll find out about it. Every single credit card transaction is there.Why are you sure?