WASHINGTON COUNTY, Mo. – A preliminary cause of death has been released after a Montana woman was found dead in the Mark Twain National Forest after being dropped off by a sheriff’s deputy.

The Mineral Area Major Case Squad said Friday that Donna Eye’s preliminary cause of death is accidential by hypothermia.

Sergeant Greg Adams, commander of the squad, said the cause of death has not been finalized though, because they’re awaiting toxiciology and other lab analysis.

Eye, who died at the age of 44, disappeared after being dropped off by a female Washington County Sheriff’s deputy.

According to a timeline released last week, authorities said Eye was released from Washington County Memorial Hospital around 6 p.m. on Jan. 8. Around 11:40 p.m., a female deputy gave her a ride to the area of Shirley School Road.

Investigators stated Eye requested to be dropped off at Shirley School Road and Forest Service Road 2375.

Eye’s brother, Ronald, thinks she was confused because his property is a half mile or mile down the road. He said she had a medical condition that sometimes limits her ability to walk and has mental health issues.

“Donna was not in any condition to make a decision for herself,” Ronald said last week.

A missing persons report was filed on January 11.

After a FOX Files investigation into the woman’s disappearance, Washington County Sheriff Zach Jacobsen activated the Mineral Area Major Case Squad on January 15.

Forest Rangers said they were never notified of Eye’s disappearance until the Mineral Area Major Case Squad activation.

Eye’s body was found in the woods on January 17, near Shirley School Road.

“We will continue the push for accountability of the public entities involved and we don’t mean a smack on the hand,” Ronald wrote in a statement. “We mean the turning in of badges, loss of licenses, credentials, and the formal charges of those public servants whose actions resulted in us mourning a life carelessly lost.”

Major Case Squad detectives will send their findings to the prosecutor for a review. Jacobsen said the prosecutor’s review will also include analyzing the deputy’s actions.

“The deputy was providing a community service by transporting her from the hospital to her residence,” Jacobsen said. “They get to Shirley School Road and Donna tells the deputy, ‘This is where I want out; this is the beginning of my driveway.’”

Jacobsen said he’ll order an internal investigation to determine if the deputy, who has been on the job for less than a year, violated any policies or procedures.

The sheriff said he wants an independent body to review the entire situation and determine whether civilians should be given rides in patrol vehicles.

“It should never be repeated without a solid review,” he said.

Jacobsen said he wants the independent group to question if it’s a service worth providing or if additional safeguards are needed.

The sheriff said he would encourage and “welcome” the entire case file to be released after the investigation is over and the case is closed.

**VIDEO FROM FOX 2’S COVERAGE ON JAN. 18**