Obviously, they don't have a solid case against the father.
In general, the FBI doesn't let criminals just slide when the scumbags steal a bunch of money and then launder it in the open if they have enough hard evidence to convict them.
In general, the FBI doesn't let criminals just slide when the scumbags steal a bunch of money and then launder it in the open if they have enough hard evidence to convict them.
Humans are creative; at that point money will be laundered through various overbilled (or even outright fabricated) medical procedures, paid for in cash.
We frequently don't catch murderers; this does not mean we should not investigate new methods of catching them.
But "we take every amount of money of which we can prove beyond doubt that it was illegitimately acquired" is like trying to deal with theft by forcing the thief to give back the goods when caught and nothing more.