South Dakota authorities are asking for help finding a father and his four-year-old son who were last seen on Interstate 90 at the eastbound Wasta rest stop. They were heading into Wall to get gas at 5:30 a.m MST Friday.

They say 54-year-old Jeff Mueztel was just released from the hospital and placed on medication. Authorities worry he may be suffering side effects from the medicine; they also say he had been displaying paranoid behavior and may have become disoriented.

Mueztel and his 4-year-old son, Myles, were supposed to meet up with family members after stopping for gas but no one has heard from them. The two were traveling in a 2005 gray Dodge pickup with Minnesota license plate UYZ556. Authorities believe he may have continued to go eastbound on I-90 towards Plymouth, Minnesota.

Mueztel is 6', 200 pounds with graying hear and blue eyes. He was wearing a blue and white striped polo shirt, khaki cargo shorts and sandals. He wears glasses with transitions lenses.

Four-year-old Myles is 3', 32 pounds with brown hair and blue eyes. He was wearing a Spiderman t-shirt that lights up when he moves, gray shorts and brown sandals.

If you have seen Mueztel, his son or the truck, please call 605-394-2151.