Cannon also said the teen sustained "significant critical trauma." The state medical examiner will begin an autopsy Sunday to determine if Haun may have been injured prior to the fall.
Haun had been at a party at a Payson home hours earlier with other teenagers, some of them classmates, where they had been drinking, Cannon said. Whatever happened likely occurred shortly before the woman found Haun's body, he said.
During the investigation, a Salem police officer found a teenager walking along the side of the road about a mile from where Haun was found. He had been at the party and argued with Haun over a common romantic interest but after talking to him extensively, investigators do not believe he was involved in what happened to Haun.
The sheriff's office said five or six teenagers could be witnesses, but none of them are talking, Cannon said. Some of the parents have even told investigators that their children are not going to talk, he added.
"It's entirely possible, too, that this whole thing was nothing criminal at all, just a tragic accident, but most of the potential witnesses are not talking to us," Cannon said.
That juveniles were drinking isn't the biggest concern to police right now they and Haun's parents want to know what happened to the teen, he said.
The woman who found the teen on the road passed the same spot on her way to work about 2 a.m. and said the body was not there at that time. As a result, police believe Haun ended up in the road sometime after that.
Investigators have surveillance footage from a nearby building that shows a vehicle passing shortly before the woman drives by. They will work Monday to enhance that video to figure out the type of vehicle and who may have been driving.