Secretary of State Rex Tillerson wipes his face during the delegation photo with leaders from Global Coalition working to Defeat ISIS at the State Department in Washington, U.S., March 22, 2017. REUTERS/Joshua Roberts

Exxon Mobil lost up to a year's worth of emails sent by former CEO and current Secretary of State Rex Tillerson under the pseudonym "Wayne Tracker," court documents show.

Exxon is under investigation by New York State Attorney General Eric T. Schneiderman for allegedly misleading shareholders and investors about risk-management issues related to climate change.

Tillerson used the Wayne Tracker alias to communicate with Exxon officials about "risk-management issues related to climate change." Tillerson — whose middle name is Wayne — allegedly used the alias for a period of seven years, between 2008 and 2015, according to Schneiderman's office.

Attorneys for Exxon wrote a letter to the court on Tuesday — highlighted by Buzzfeed's Mike Hayes — describing how the emails were lost. Assistant State Attorney General John Oleske called the letter a "bombshell," in a court hearing on Wednesday, alleging that Exxon failed to comply with the original subpoena in 2016.

The letter describes how Tillerson's "Wayne Tracker" emails were exempted from a "file sweep" that protects personal emails on Exxon's server from automatic deletion. The emails, ranging from September 5, 2014 to September 16, 2015, were classified by Exxon's system as non-personal, and were wiped.

A secondary search, with broader terms, turned up some of the missing "Wayne Tracker" emails, though none from September 5, 2014 to November 28, 2014.

"Tillerson was the only custodian who used a secondary account, and ExxonMobil is aware of no email account, other than the Wayne Tracker account, for which this issue has arisen," the letter reads.

Darren Woods, Chairman & CEO, Exxon Mobil Corporation attends a news conference at the NYSE. Thomson Reuters

In the Wednesday court hearing, Exxon was ordered by Justice Barry Ostrager to produce all relevant management documents by March 31.

Exxon was further ordered by the court to produce sworn affidavits by April 10 regarding everything the company's lawyers have done to produce the management documents, as well as all the information they know about what was lost. They must also swear that they have produced everything owed to the attorney general's office under the original subpoena.

"16 months after our initial subpoena, Exxon was ordered by the court to finally produce all documents from its management committee, and to provide clear answers to the AG’s office about any documents — including those from alias accounts — that were lost,"Amy Spitalnick, the press secretary for the New York attorney general, told Business Insider.

Exxon was ordered to meet with the attorney general's office to figure out what can be done to recover the lost emails.

Exxon spokesman Alan T. Jeffers told Business Insider that the court "repeatedly stated" that the company had provided the attorney general with a "comprehensive response that addressed the attorney general's concerns."

"[W]e do not expect our ability to produce relevant documents to be significantly impacted because Tillerson’s secondary account was searched after receiving the subpoena, and many of the emails from the secondary account were also available from Tillerson’s primary account or from email accounts of other employees he communicated with, which were on litigation hold," Jeffers said.