FAYETTE COUNTY — A 31-year old former ISP trooper pleaded guilty Tuesday to three counts criminal sexual assault and was sentenced to 18 years in the Illinois Department of Corrections to be served at 85%.

James Dierkes was charged in the two separate cases accusing him of incidents alleged to have occurred while he worked at Okaw Area Vocational Center in Vandalia in 2016.

Dierkes later left the employment of the Vandalia school district to join the Illinois State Police. Once he was charged, the State Police fired him.

In December of 2019, a report was forwarded to the State’s Attorney about possible sexual contact between Mr. Dierkes and Victim A during his tenure as a teacher at Vandalia High School. An investigation led officers to another victim.

He was then charged with the first two charges against him: Class 1 felony criminal sexual assault of a person between the ages of 13 and 17 who was under his supervision and Class 2 felony criminal sexual abuse of a person between the ages of 13 and 18.

But before his preliminary hearing in that case, Dierkes was charged with an additional nine Class 1 felony sex offenses connected with his time as an educator.

He was scheduled to be tried before a jury on January 18 but instead entered into a plea agreement with the state on the three charges in exchange for the eight other charges being dismissed.

“The way that Mr. Dierkes used his position as a teacher to violate the trust of his students, their parents, and the community is inexcusable,” stated Fayette County State’s Attorney Joshua Morrison. “I am pleased that Mr. Dierkes has pled guilty and spared the victims from having to relive his abuse at trial. It is always my aim to do justice, and I believe that justice has been found in this case.”

Both victims have been consulted regarding this plea agreement and were present in the courtroom when the plea occurred.

This investigation was completed by the Illinois State Police and Vandalia Police Department.