(AP) — Officials are awaiting results of toxicology tests to determine what killed an 18-year-old whose body was found at a friend’s house in the eastern Nebraska town of Waverly.

Lancaster County Sheriff Terry Wagner said Monday that an autopsy didn’t find any signs of trauma on the body of William “Billy” Tucker.

Tucker and three friends had gone to a Lincoln party on Saturday night and fell asleep there. Wagner says that around 8:30 a.m. Sunday the four went to the Waverly home of one of them. Wagner says Tucker was unresponsive when a 20-year-old woman tried to wake him around 1:45 p.m. Sunday. Waverly rescue workers who responded to a 911 call said Tucker had died.

Tucker graduated from Ashland-Greenwood High School this past spring.