The bodies were discovered Saturday by a snowmobiler in Ogemaw County. All three were outside a pickup truck, which appeared to be stuck on a rock, Sheriff Brian Gilbert said.
Autopsies are scheduled for Wednesday, Gilbert said.
"We haven’t found anything else out," the sheriff said Tuesday. "The autopsy will tell us the story. The unanswered questions will come out."
Amanda Pomeroy, Douglas Dougherty and son Jacob lived in Bay City and were reported missing on Jan. 16. The boy was under a year old. They were last seen visiting family in Ogemaw County.