BALSAM LAKE, Wis. (AP) – Authorities say a Wisconsin toddler found dead in the trunk of a car likely died of hyperthermia.  The Polk County Sheriff’s Department released a statement Friday afternoon summarizing preliminary results of an autopsy on 2-year-old Isaiah Theis. The autopsy found the boy was normally developed and well-nourished and had suffered no life-threatening injuries or bone fractures. He also wasn’t sick.  The statement listed the cause of death as probable hyperthermia, a condition where body temperature spikes. The manner of death is still under investigation.   Toxicology reports are pending.  The boy disappeared Tuesday night. A sheriff’s deputy found his body in the trunk of a locked car outside the boy’s home near Centuria late Wednesday evening after a day of blistering heat.