Officials are ramping up their investigation into who leaked a Supreme Court opinion draft by requiring clerks to hand over phone records and sign affidavits.

The Washington Examiner reports:

Following the leak of a draft opinion in Dobbs v. Women’s Health Organizationon May 2 that signaled the majority of high court justices were prepared to return the question of abortion’s legality over to the states, Chief Justice John Roberts reportedly met with law clerks as a group after the break, according to CNN Tuesday.

While it is not clear whether those who work under the justices were interviewed individually, the sources told the outlet some of the clerks are particularly alarmed by the course of action and have considered whether to hire outside counsel.

“The affidavit may be a greater concern for the leaker,” George Washington University Law professor Jonathan Turley tweeted on Tuesday.

“After all, the leaker may have avoided using the cellphone or creating digital tracks. The affidavit is a sworn statement to federal investigators. If false, it could constitute a federal crime,” Turley added.

The court’s marshal, Gail Curley, is leading the probe. Curley has the authority to make arrests over violations of state or federal law. However, any potential decision on prosecution related to the leak would likely come from the Department of Justice.