SPRINGFIELD, Ill. (NEXSTAR) — Attorney General Kwame Raoul’s office confirmed Nicor Gas is under investigation in an email on Friday afternoon.

Assistant Attorney General James Gale penned a letter refusing to release public sought under the Freedom of Information Act, saying the records are “related to an ongoing investigation and potential law enforcement proceedings.”

“Releasing the records would interfere with an ongoing investigation and potential law enforcement proceedings of this office,” Gale wrote.

The Illinois Attorney General’s Office refused to release public records from state agencies IDNR, IEPA, or the Illinois Commerce Commission that pertain to Nicor Gas violations because it “would interfere with an ongoing investigation and potential law enforcement proceedings.”

The public records request sought “violations notices, complaints, citations, and recommendations for further action, fine, investigation, litigation, or other enforcement request” from the Illinois Department of Natural Resources, Illinois Environmental Protection Agency, or the Illinois Commerce Commission.

Nicor Gas did not immediately respond to a request for comment.

Raoul’s office did not specify the nature of the ongoing investigation, but a memo drafted in December of 2017 by the Illinois Department of Natural Resources said, “Ongoing leakage of natural gas at the NICOR Gas natural gas storage facility in Ancona, Illinois, requires enforcement action by the Attorney General’s office.”

In October of 2020, Raoul’s office said, “Our office has not received referrals from the Illinois Environmental Protection Agency or the Illinois Department of Natural Resources.”

Jen Walling from the Illinois Environmental Council reacted to the report in October, citing “extremely troubling” concerns over the “immediate, short-term pollution.”

A lawsuit that initially sought to shut the Ancona gas field down has stalled.

The Illinois House Energy and Environment Committee recently approved a plan to increase monitoring and regulation of leaking natural gas fields.

A former state inspector says mysterious bubbles in farmland water wells and creek beds are the result of an active methane leak emanating from a massive underground natural gas storage facility operated by Nicor Gas.

Professor Don Wuebbles, an atmospheric science expert at the University of Illinois, explained the impact methane emissions can have on the environment.

A massive natural gas field in Ancona, Illinois, quietly leaks up to 20k tonnes of methane per year.

At a separate facility in Troy Grove, Illinois, lab reports showed Nicor dumped tons of carcinogenic wastewater into farm fields above aquifer recharge zones. At last report, the local health departments had not tested the drinking water in private wells that sit atop that gas field, though emails from the state and county public health officials suggested they should run tests.

Lyndsay Jones contributed to this report.