HAMILTON, ILL. -- A 2 1/2 year investigation into the manufacture of methamphetamine led to the arrest of two men and more arrests are expected.

The arrests occurred at about 3 a.m. Monday.

Richard L. Grotts, 49, was arrested at his home at 810 Allen St. in Hamilton on a federal arrest warrant that charges him with conspiracy to manufacture methamphetamine.

Steve T. Sheffler, 50, of 720 E. County Road 1200 in rural Hamilton, was arrested on charges of conspiracy to manufacture methamphetamine.

Investigators discovered materials used to manufacture the drug at both homes, the Hamilton Police Department said. Guns and homemade explosives were also found at Sheffler's home, the Hamilton Police Department said.

The early morning raid involved a number of of law enforcement agencies and the use of a search helicopter.

Officials from the Warsaw Police Department, Lee County Iowa Narcotics Task Force, the Illinois State Police Tactical Response Team, the Hancock County Sheriff's Office, the Illinois State Police Meth Response Team, the Illinois Secretary of State Police Bomb Squad, the Illinois State Police Air Unit, and the U.S. Attorney of the Central Illinois assisted in the investigation.