The New York attorney general says that while Secretary of State Rex Tillerson was CEO of Exxon Mobil he used an alias in emails to talk about climate change.

The attorney general, Eric Schneiderman, made the accusation in a letter to a New York court Monday. He is investigating whether the company deceived investors and the public by hiding for decades what it knew about the link between fossil fuels and climate change.

Schneiderman says Exxon failed to disclose that Tillerson used an account named “Wayne Tracker” to send and receive emails about issues including risk management related to climate change. Wayne is Tillerson’s middle name.

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ExxonMobil released a statement to CBS News denying that the emails from the Tracker address were just related to climate change.

“Media reports indicating that emails to or from this address were exclusively for climate-related topics are false,” the statement read.

The oil and gas giant also said that Tillerson’s main email address received “a large volume” of messages, and the Tracker email was used “for secure and expedited communications between select senior company officials and the former chairman for a broad range of business-related topics.”

ExxonMobil also said that it has provided over 2.5 million pages of documents to Schneiderman in response to the attorney general, adding, “We will respond to the claims in the letter through the appropriate court process and not via the media.”

CBS News’ Kylie Atwood contributed to this story