Devlin made the plea via video Tuesday morning in Franklin County. He remains at the county jail.
It was the second time Devlin has pleaded not guilty in Franklin County. That's because a grand jury last week indicted the 41-year-old suspect, requiring a new arraignment.
He has also pleaded not guilty in nearby Washington County for the 2002 abduction of Shawn Hornbeck. Both boys were found January 12th at Devlin's apartment in suburban St. Louis.
Devlin also faces charges in St. Louis County, and was charged last week in a federal indictment for allegedly making pornographic photos and videos of a boy.