In a rare glimpse of what it might be like to be their clients, Mayer Brown partners Richard Ben-Veniste and Andrew Frey offered some words of wisdom for lawmakers Tuesday on their investigation into Russian interference in the 2016 election.

Ben-Veniste, based in Washington, D.C., and Frey, of the firm's New York office, spoke at a hearing before the Senate Judiciary Committee's Subcommittee on Crime and Terrorism about lessons learned in their experiences working on congressional investigations when there was also an ongoing criminal investigation. The lawyers were advising the lawmakers on working with FBI Special Counsel Robert Mueller III as he conducts his concurrent investigation on Russian interference and possible collusion with President Donald Trump's campaign.

Both attorneys are no strangers to special prosecutors and congressional investigations—Ben-Veniste was a lead prosecutor on the Watergate Special Prosecution Force and chief counsel of the Senate Whitewater Committee and Frey was assistant to the solicitor general under President Richard Nixon and then deputy solicitor general from 1973 to 1986. The lawyers testified alongside Danielle Brian, executive director of the Project on Government Oversight, and University of Baltimore law professor Charles Tiefer.