COLUMBUS, Ohio (AP) — Attorney General Mike DeWine’s office is investigating the business practices of Chesapeake Energy Corp., a key player in the state’s burgeoning natural-gas market.

In a June 12 letter to the environmental watchdog group Ohio Citizen Action, DeWine said he launched in April a preliminary review of “unfolding disclosures” of activities by the Oklahoma City-based company and its CEO Aubrey McClendon.