Two Democrats have sent a letter to former federal judge Michael Chertoff, who reviewed the Supreme Court’s probe into last year’s extraordinary leak of a draft opinion, asking for more details on Chertoff’s ties to the court.

Sen. Sheldon Whitehouse (D-R.I.) and Rep. Hank Johnson (D-Ga.), both of whom have criticized the probe and have called for strengthened ethics rules among the justices, sent the letter late last month after CNN reported that Chertoff had long-standing financial ties with the court.

The leak investigation did not conclusively identify who leaked the bombshell draft majority opinion overturning Roe v. Wade.

Progressives have criticized the probe as letting the justices off the hook, comparing how court employees were asked to sign sworn affidavits and provide their devices to how the marshal said she “spoke” to the justices, in which they were “asking questions and answering mine.”

Chertoff, who also previously served as Homeland Security secretary, described the court’s investigation as “thorough” after being asked to independently review the probe, but the disclosure of his financial ties has led to scrutiny from the two lawmakers.

“The Court’s failure to explain adequately why it felt a third-party review was necessary, how it chose that reviewer, and its preexisting relationship with the reviewer all warrant additional clarity,” Whitehouse and Johnson wrote. “In this purely administrative matter, our committees have an appropriate oversight interest, and we would be grateful for more clarity about your role in this matter and relationship with the Court.”

Days after the court issued its public report about the probe and a statement from Chertoff, CNN reported that the court in recent years privately contracted with The Chertoff Group for security assessments, providing Chertoff’s group with more than $1 million in payments.

The letter, which was first reported by CNN, asks Chertoff how he became involved in the investigation, the extent of his group’s prior work and if he maintains personal relationships with any justices.

Chertoff succeeded Justice Samuel Alito, the author of last year’s abortion decision, as the U.S. Attorney for the District of New Jersey in 1990. They later served together as judges on the 3rd U.S. Circuit Court of Appeals for more than a year.

Ellen Murray, a spokesperson for The Chertoff Group, said the organization received the letter and will respond.

“As you may know, we are working on legislation regarding the internal investigative capabilities at the Court,” Whitehouse and Johnson wrote. “Your responses to these questions will help inform any steps that Congress may take to ensure that future investigative matters are properly handled.”