TEXARKANA — A former youth baseball coach faces up to 10 years in prison after pleading guilty Thursday a federal charge related to sexual assaults on minors dating back more than 20 years.

Walter Richard Roberts, 62, of Texarkana, pleaded guilty before U.S. District Judge Susan O. Hickey to a single count of transporting a minor in interstate commerce with the intent to engage in a sexual activity.

Also Thursday, an Altus man pleaded guilty in a child porn case and was sentenced to 40 years.

From 1986 to 1994, Roberts was a youth baseball coach in Texarkana.

According to documents filed in U.S. District Court, Roberts engaged in an extensive pattern of sexual assault that spanned several years. In 1986, prosecutors said, Roberts transported two boys, ages nine and 10, from the Arkansas side of Texarkana to a supply store on the Texas side where he parked and assaulted the boys in the back of a van.

The government said the older boy had been assaulted by Roberts when he was nine during a trip to Wright Patman Lake in Texas.

Roberts admitted to sexually assaulting a third boy, who was nine or 10 years old at the time, during a fishing trip to Beard’s Lake in Arkansas in 1988 or 1989.

"There are no cases more important than those in which children are victims," U.S. Attorney Conner Eldridge said. "The pattern of sexual abuse that this defendant committed is reprehensible. His conviction today is another step towards holding him accountable. We will continue to aggressively prosecute those who victimize children in our communities."

Meanwhile, Kenneth Gene Mendenhall, 39, pleaded guilty in Franklin County Circuit Court to four counts of distributing, possessing or viewing matter depicting sexually explicit conduct involving a child, according to the state attorney general’s office.

Circuit Court Judge William Pearson sentenced Mendenhall to 10 years in prison on each count, with the sentences to run consecutively.