Critics of the fund are concerned that January 6 rioters may end up with some of the money.
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Fitzpatrick wants the Department of Justice to explain where that money is coming from, and whether people convicted of crimes may get payouts.
He demands answers by June 1.
The so-called "Anti-Weaponization Fund" is part of a settlement between President Trump and the IRS over the 2019 leak of his tax returns.
It was not authorized by Congress and does not have any judicial oversight.