Ada County officials said an out-of-town prosecutor is looking into an agreement between commissioners and Dynamis Energy.
The Bannock County Prosecutor is looking into allegations that commissioners and Dynamis violated the state's open-meeting law.
The company wants to build a plant that would turn trash into energy at the Hidden Hollow landfill.
Neighbors oppose the project, saying it would contaminate the air.
Dynamis officials have said that's not true.