Bill Priestap, a 20-year veteran of the FBI, will exit the agency at the end of the year, according to a new report.

Priestap, the assistant director of the Federal Bureau of Investigation’s counterintelligence division, has decided to retire from the bureau, the Wall Street Journal reported.

He was involved with the investigation regarding the unauthorized email server of 2016 Democratic presidential candidate Hillary Clinton that she used while she was secretary of state and the investigation examining Russian interference in the 2016 election and whether the Trump campaign colluded with the Kremlin.

With officials like former FBI Director James Comey and Deputy Director Andrew McCabe no longer at the FBI, Priestap is currently the last high-ranking official at the FBI who originally worked on both investigations.

The investigations have come under fire from both Republicans and Democrats, who have cited mismanagement issues in both. For example, Democrats have expressed frustration that the FBI shared they were conducting an investigation into Clinton prior to the election but waited until after the election to disclose they were also investigation Russian interference.

Meanwhile, Republicans fault the FBI for going easy on Clinton and not charging her with any wrongdoing and have claimed that the FBI inappropriately obtained a surveillance warrant to monitor a Trump campaign aide.

The FBI told the Journal that Priestap’s retirement was unrelated to the 2016 investigations and said he “became eligible to retire and has chosen to do so after 20 years of service.” It’s uncertain what Preistap plans to do following his retirement.