A substitute teacher at a Montessori charter school in Chaska was charged Tuesday with sexually touching two students.

Matthew VanHecke, 34, told police he touched the two girls, now ages 8 and 9, at before- and after-school programs at World Learner School, a public charter school serving elementary-and middle school students. The incidents occurred during the 2012-13 school year, according to the criminal complaint.

The charges, two felony counts of criminal sexual conduct, were filed in Scott County instead of Carver County because of a potential conflict of interest.

VanHecke told police that he has always had "these thoughts" about "little kids" in his head, the complaint said.

He admitted he touched three girls at the charter school but is charged with assaulting two.

Because VanHecke has been employed in various classroom environments throughout the Chaska school system, investigators are concerned that there may be other victims, Chief Deputy Scott County Attorney Ron Hocevar said.

"We take every criminal case very seriously," he said. "But any criminal activity involving minor children is always particularly disturbing."

VanHecke worked as a substitute paraprofessional for the Eastern Carver County School District from Oct. 30 through Dec. 11. He was under the supervision of a licensed teacher, a district spokesman said.

He passed a criminal-background check and the school district had no complaints against him, the spokesman said. World Learner School isn't part of the school district.

Anyone with additional information is urged to contact Chaska police detective Tracy Perlich at 952-448-4200.