SUMMIT COUNTY, Colo. The Summit County Sheriffs Office announced Monday it has closed its investigation into a deadly vehicle explosion at a trailhead last March, concluding there is no evidence of criminal involvement.Despite these findings, the sheriffs office did not provide details as to what caused the explosion, which left 51-year-old Dillon resident William Earl Busch dead.The vehicle was found ablaze at the Upper Straight Creek Trailhead on the morning of March 6 after several reports of an explosion, smoke and fire in the area, according to the sheriffs office.Buschs body was recovered from the badly charred vehicle after crews extinguished the blaze. The cause and manner of his death have not been released.Sheriff Jaime FitzSimons said the scene required extensive work, but investigators ultimately found no indication the death was caused by another person.The monthslong investigation included assistance from the ATF, the Colorado Bureau of Investigation, and the Division of Fire Prevention and Control. ...read more read less