GRNAD JUNCTION, Colo. -- Mesa County sheriff's investigators are looking into the death of a teenager found dead in his bed.

Authorities say Zachary Glen Sockman, 18, was found unresponsive at home Monday morning. Sheriff's officials said his stepfather tried to wake him, but the teen had died sometime overnight.

Deputy coroner Kim Hollingshead said homicide and suicide have been ruled out, but the cause of death is still unknown.

"It appeared to be a nontraumatic death," Hollingshead told the Grand Junction Sentinel. She said it could be a case of death from natural causes.

"It's not very usual that teenagers pass away, but they do. We won't have any idea for probably several weeks on the exact cause of death," Hollingshead said.

Blood and toxicology test results are pending, but won't be available for at least one or two weeks.

Grand Junction High School assistant boys soccer coach Ralph Wahlers said Sockman recently returned from a trip to Florida to visit his biological father.

Wahlers said Sockman told him he planned to enter the Air Force.

Wahlers was told Sockman went to bed feeling sick, "something related to sinuses," according to the newspaper.

"This isn't supposed to happen to a healthy 18-year-old," Wahlers said.

Sockman lived in the home with his mother, stepfather and two siblings.