Secretary of State Rex Tillerson used a pseudonym to discuss climate change in emails when he was the chairman and chief executive of Exxon Mobil, the New York attorney general's office has found.

As part of Attorney General Eric Schneiderman's investigation into whether the energy company was not forthcoming with shareholders and the public about the risks of climate change, Exxon Mobil says it has turned over 2.5 million pages of documents. According to Schneiderman's office, some 60 documents from the company included the email address Wayne.Tracker@exxonmobil.com, with "Wayne Tracker" being an alias Tillerson used from at least 2008 to 2015.

Wayne is Tillerson's middle name. Before he was nominated by President Donald Trump in December to be the nation's top diplomat, Tillerson spent four decades at Exxon, including 11 years as its chairman and CEO until he stepped down on Jan. 1.

"Despite the company's incidental production of approximately 60 documents bearing the 'Wayne Tracker' email address, neither Exxon nor its counsel have ever disclosed that this separate email account was a vehicle for Mr. Tillerson's relevant communications at Exxon," Senior Enforcement Counsel John Oleske said in a letter to New York Supreme Court Justice Barry Ostrager, who is overseeing probe proceedings.

The letter, according to Reuters, asked Ostrager to order Exxon to state whether emails from "Wayne Tracker" and 34 other accounts assigned to other company executives and board members had been properly preserved.

"Exxon's top executives, and in particular, Mr. Tillerson, have made multiple representations that are at the center of OAG's (attorney general's office) investigation of potentially false or misleading statements to investors and the public," the letter said.

In a statement Monday, Exxon spokesman Alan Jeffers said the "Wayne Tracker" email address "was put in place for secure and expedited communications between select senior company officials and the former chairman for a broad range of business-related topics."

Reports "indicating that emails to or from this address were exclusively climate-related are false," he said, according to The Wall Street Journal.