Utah medical examiner on Wednesday completed an autopsy on Tammy Daybell
The results are not being released to the public, authorities said
Fremont County Sheriff Len Humphries said the report is being used as 'evidence in an open and ongoing investigation'
The Idaho Attorney General is investigating Tammy's ex-husband Chad Daybell and his new wife Lori Vallow in connection with her death
Tammy was initially said to have died of natural causes in October 2019 after Chad refused an autopsy
Two weeks later, he married Vallow, whose husband also died months before
An investigation was launched into both deaths after Vallow's children JJ and Tylee were reported missing later that year