WATERLOO - A Waterloo man serving prison time for abusing young boys in the 1990s has pleaded guilty to sex charges in Minnesota.

Thomas Lee Drilling, 68, pleaded to first-degree criminal conduct in Cass County on Aug. 21.

Sentencing will be at a later date, and the crime carries up to 30 years in prison.

The charges stem from fishing trips to Minnesota Drilling allegedly took with a 15-year-old local boy in 1995.

Drilling is currently serving a 10-year prison sentence for Iowa charges at the Mount Pleasant Correctional Facility.

In 2007 he pleaded to sexual abuse for abusing a different boy at his home in the early 1990s.

Authorities said Drilling met the child at a school where he participated in a Partners in Education program.