Why did the father drive away with his son, Jessy, from a family hunting camp after midnight down a steep, dangerous Jeep trail in Garfield County?

Transfer Trail is described as "dangerous" and "scary" on off-road vehicle Web sites. It is rated "difficult," and off-road drivers are cautioned that "travel is recommended during the day and in dry weather."

The trail can be steep, narrow and "very rocky" and "very rutted," according to the White River National Forest Web site. The weather was dry the night of the accident.

Investigators are still interviewing family members and waiting a few weeks for toxicology test results before commenting further on what is now called a death investigation, said Garfield County deputy Tanny McGinnis, sheriff's spokeswoman.

Such tests would reveal whether alcohol, drugs or prescription medication played a role in the deadly plunge near the treacherous trail in the Flat Tops Wilderness.

An autopsy was conducted Tuesday on the father and son in Grand Junction. The results were not immediately available.

Family members, who were meeting with coroner officials Tuesday in Glenwood Springs, could not be reached for comment.

Investigators said they believe that the "modified" Jeep's left tires slipped over the edge of Windy Point, a 10,218-foot overlook, as Blissett tried to negotiate a narrow road off Transfer Trail.

"His tires went off the side of the road and he wasn't able to pull it back on," said Chandra Mortensen, a Garfield County deputy coroner. "The tire tracks show the left tires went off the side of the road and he went over from there."

Investigators said they believe the crash occurred between midnight and 1 a.m., because that is when Blissett left camp, driving south down the steep trail toward Glenwood Springs.

The father and son were thrown out as the vehicle rolled repeatedly.