ST. CHARLES – A four-month police investigation involving child pornography ended with the arrest of a 51-year-old St. Charles man Monday, according to police.

Gary L. Harris, of 1809 Howard St., was charged with four counts of aggravated child pornography and possession of marijuana and cocaine with intent to manufacture or deliver, police said.

Naperville and Downers Grove police departments were investigating the sharing of child pornography in a file sharing network when investigators determined Harris’ involvement. During their investigation, they determined the sharing involved a St. Charles resident and provided an IP address and a DVD, to St. Charles police investigators.