U.S. Attorney spokesman Ryan Holmes says federal authorities were serving search warrants on the sheriff.
The United States filed an appeal Monday after a federal judge placed former VCSC employee Frank Shahadey on in home detention as he awaits his trial.
Two Vigo County Schools Corporation employees are charged with theft for a kickback scheme worth thousands of dollars.
The FBI raided the Vigo County School Corporation offices in June. The FBI arrested Franklin Fennell early Wednesday morning.
The FBI questioned lawmakers and an e-cigarette producer about the creation of the state's vaping law at the end of August.
The law has given seven producers control of the Indiana market, shutting out dozens of other manufacturers.
FBI agents seized computers, thumb drives and recordings from the district's office in June.
Donnelly wouldn't provide many specifics about the FBI's counterterrorism efforts.
The FBI says the 18-year-old planned to travel overseas and join ISIL.
Agents raided the school corporation's administrative offices, transportation center and information technology center.