A Massachusetts judge has refused to excuse ExxonMobil Corp. (NYSE: XOM) from a request by the state's attorney general to hand over decades worth of documents on its views on climate change, state officials said on Jan. 12.

The decision by Massachusetts Superior Court Judge Heidi Brieger denying Exxon's request for an order exempting it from handing over the documents represents a legal victory for Massachusetts Attorney General Maura Healey, who is investigating the world's largest publicly traded oil company's climate policies.

"This order affirms our longstanding authority to investigate fraud," Healey said on Twitter following the decision, adding that Exxon "must come clean about what it knew about climate change."

Exxon spokesman Alan Jeffers said the company was "reviewing the decision to determine next steps."

Healey is one of two state prosecutors, the other being her counterpart in New York, investigating whether Exxon knowingly misled its shareholders and the public as to what it knew about climate change.

The investigations follow separate reports by online news publication Inside Climate News and the Los Angeles Times showing that Exxon worked to play down the risks of climate change despite its own scientists having raised concerns about it decades earlier.

The news came on the day former Exxon CEO Rex Tillerson faced a U.S. Senate confirmation hearing on his nomination to serve as President-elect Donald Trump's secretary of state.

Asked during the hearing if he believed human activity was contributing to climate change, Tillerson did not answer yes or no, but said, "the increase in greenhouse gas concentrations in the atmosphere are having an effect. Our abilities to predict that effect are very limited."