MONTGOMERY COUNTY, Mo. – A guilty conscience prompted a High Hill, Missouri, man to surrender Monday to the Missouri State Highway Patrol for crimes related to child pornography.

According to a probable cause statement from the highway patrol, an investigator with the MSHP’s Division of Drug and Crime Control was searching for sex offenders sharing child sexual abuse material online in December 2024. The investigator discovered a file containing child pornography connected to a specific IP address.

In August 2025, investigators downloaded additional files of child pornography from the same IP address used in December 2024.

The highway patrol said investigators traced the IP address to the home of Matthew A. Thomson.

On Sept. 5, investigators went to Thomson’s residence with a search warrant, but he was not home at the time. Authorities found Thomson at his job at a St. Louis County hospital and questioned him about their investigation. They also confiscated his cell phone but discovered a factory reset had been initiated.

Days later, Thomson, 49, walked into the Troop C Headquarters in Weldon Spring and asked to speak with an investigator, saying that his conscience had been weighing on him since last week.

The highway patrol said Thomson confessed to downloading and viewing child pornography for the last 25 years, and that he preferred to view content showing girls between the ages of 10 and 16.

The Montgomery County Prosecuting Attorney’s Office charged Thomson on Tuesday with three counts of first-degree promoting child pornography and one count of possession of child pornography. Thomson remains jailed without bond. He’ll make his first appearance in court on Thursday, Sept. 11.