Justice Clarence Thomas failed to disclose a 2014 real estate deal he made with a GOP megadonor, according to a ProPublica report published Thursday.

See Also:  Former President Donald Trump's indictment could make turnout in Wisconsin's Supreme Court election 'unstable'

The deal involved the sale of three properties in Savannah, Georgia, that were owned by Thomas and his relatives to the megadonor, Harlan Crow, according to ProPublica, which said that tax and property records showed that Crow made the purchases through one of his companies for a total of $133,363.

See Also: former President Trump and special counsel Jack Smith bringing a "new level of aggressiveness and urgency" at the Department of Justice

But Thomas "never disclosed his sale of the Savannah properties," the report said, noting that ethics law experts told the outlet that his failure to report it "appears to be a violation of the law."

See Also: Trump's attorney Joe Tacopina: I anticipate motion to dismiss charges

"The transaction marks the first known instance of money flowing from the Republican megadonor to the Supreme Court justice," ProPublica said in its report.

See Also: "The View" co-host Joy Behar says the quiet part OUT LOUD about Trump vs DeSantis

Thursday's report comes on the heels of a bombshell investigation published last week by ProPublica that detailed Thomas and his wife's luxury travel with the Crows, which included trips on the donor's yacht and private jet. The justice also did not disclose that travel, and he later defended the decision not to, saying in a rare statement last week that he was advised at the time that he did not have to report it.

See Also: MSNBC contributor Jason Johnson claimed that when people think of Florida, they mostly think of "crystal meth and alligators."

CNN has reached out for comment from the Supreme Court and Thomas.

Crow said in a statement to CNN that he purchased the properties to "one day create a public museum at the Thomas home dedicated to telling the story of our nation's second black Supreme Court Justice."

See Also: Kamala Harris dismisses unpopularity among Democrats ahead of 2024: 'Political chatter'

He added that he made the purchases at "market rate based on many factors including the size, quality, and livability of the dwellings."

See Also: Senator Bernie Sanders also talks about his new book 'It's OK to be Angry about Capitalism.'

Though two of the properties were later sold by Crow, according to his statement, the real estate magnate still owns the property on which Thomas' elderly mother lives. Citing county tax records, ProPublica said one of Crow's companies pays the "roughly $1,500 in annual property taxes on Thomas' mother's house," which had previously been paid by the justice and his wife, Ginni.

See Also: 'I call him Baby Trump': Al Sharpton on protesting Ron DeSantis administration's blocking of Black history

Experts told ProPublica that Thomas' failure to disclose the 2014 deal raises more questions about his relationship with Crow.

"He needed to report his interest in the sale," Virginia Canter, a former government ethics lawyer who now works for Citizens for Responsibility and Ethics in Washington (CREW), told the outlet. "Given the role Crow has played in subsidizing the lifestyle of Thomas and his wife, you have to wonder if this was an effort to put cash in their pockets."

See Also: Former President Donald J. Trump Delivers Remarks at Mar-a-Lago

The report has already prompted the watchdog group to call for an investigation into Thomas' decision not to disclose the real estate deal and the various trips and gifts.

See Also: Manhattan District Attorney Alvin Bragg makes the most incredible statement of the day

In a letter sent Friday to Chief Justice John Roberts and Attorney General Merrick Garland, CREW said that Thomas may have violated the Ethics in Government Act. The group said Roberts also should investigate whether Thomas violated his "ethical obligations" under Judicial Conference regulations.

See Also: 'Extreme abuse of power': Ocasio-Cortez slams abortion pill ruling

In the wake of last week's revelations, congressional Democrats have also called for an investigation into the matter and for a stronger ethics code for the justices, and some federal judges have also spoken out.

See Also: On CNN's State of the Union, HHS Secretary Xavier Becerra doesn't say whether the FDA should ignore a federal judge's ruling to block access to abortion medication but tells Dana Bash that "everything is on the table."

Earlier this week, the Senate Judiciary Committee announced it plans to hold a hearing "on the need to restore confidence in the Supreme Court's ethical standards," and at least one watchdog group has urged lawmakers to call Thomas as a witness in the upcoming hearing.