Thomas has attended at least two Koch donor summits, putting him in the extraordinary position of having helped a political network that has brought multiple cases before the Supreme Court.

In response to ProPublica reporting, the friend said Crow covered two years of schooling for the teen, which would amount to roughly $100,000 of undisclosed gifts. Meanwhile, Democrats renewed calls for judicial ethics overhaul.

Crow paid for private school for a relative Thomas said he was raising “as a son.” “This is way outside the norm,” said a former White House ethics lawyer.

The transaction is the first known instance of money flowing from Crow to the Supreme Court justice. The sale netted the GOP megadonor two vacant lots and the house where Thomas’ mother was living.

The lawmakers said the chief justice was duty-bound to conduct a “swift, thorough, independent and transparent investigation” of Thomas’ undisclosed travel with billionaire Harlan Crow in order to “safeguard public faith in the judiciary.”

In response to a ProPublica report, Thomas explained why he did not disclose lavish travel provided by billionaire Harlan Crow. But legal experts maintain the justice was required to make these disclosures.