(AP) — Toxicology tests show an 18-year-old who was pronounced dead at the Waverly home of a friend died because he smoked too much synthetic marijuana.

The Lancaster County Sheriff’s Office said Friday that tests also showed that William “Billy” Tucker had been drinking alcohol, but the pathologist didn’t conclude that alcohol directly contributed to Tucker’s death.

Tucker and three friends had gone to a Lincoln party on Oct. 12 and fell asleep there. Authorities say that around 8:30 the next morning, the four went to the Waverly home of one of them. Tucker was unresponsive when a 20-year-old woman tried to wake him that afternoon.

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