A former FBI lawyer has pleaded guilty to altering a document related to the secret surveillance of a former Trump campaign adviser during the Russia investigation.

Kevin Clinesmith is the first current or former official to be charged in a special Justice Department review of the investigation into ties between Russia and Donald Trump’s 2016 presidential campaign.

Clinesmith on Wednesday pleaded guilty to a single false statement charge, admitting that he doctored an email that the FBI relied on as it sought court approval to eavesdrop on former Trump campaign aide Carter Page in 2017.

Clinesmith resigned from the FBI before an internal disciplinary process was completed.

The case highlights broader problems with the FBI’s surveillance applications on Page, an issue that has long animated critics of the Russia investigation.

Charging documents filed on Friday say Clinesmith altered an email he received in June 2017 from another government agency to say that Page was “not a source” for that agency, then forwarded it along to a colleague.

The FBI relied on Clinesmith’s representation in the email when it submitted its fourth and final application to the Foreign Intelligence Surveillance Court to secretly eavesdrop on Page on suspicions that he was a potential Russian agent.

Information about any relationship Page may have had with another government agency would have been important to disclose to the FISA court to the extent it could have helped explain, or reframe in a less suspicious light, Page’s interactions with Russians.

Clinesmith’s attorney, Justin Shur, said in a statement last week that Clinesmith regretted his actions and had not intended to mislead the court or his colleagues.

A Justice Department inspector general report issued last December found significant errors and omissions in the four applications that the FBI submitted to eavesdrop on Page.

A Senate intelligence committee report Tuesday that examined links between Trump associates and Russia also identified flaws in the FBI’s surveillance, including its reliance on a dossier of opposition research compiled by a former British spy whose work was funded by Democrats.