Washington( CNN) Just over a week after President Donald Trump fired James Comey as FBI director, the Department of Justice appointed Comey’s predecessor, former FBI Director Robert Mueller, as special attorney for the investigation into Russian attempts to influence the 2016 election.

The two former FBI chiefs have a unique relationship, stemming in big part from operating side by side during a major showdown with the Bush administration.

By sheer coincidence, the coming week marked 10 years since Comey gave his bombshell testimony before the Senate Judiciary Committee about the showdown with President George W. Bush’s White House. It began in 2004, when Comey refused to reauthorize an NSA snooping program.