WEST MEMPHIS, Ark. (NewsNation) — The preliminary cause of death for a Kansas mother of three and church pastor’s wife who disappeared while driving from Kansas to Alabama has been released by Arkansas deputies.

Positive identity of the body is pending but deputies believe they found Marilane Carter dead in her car which was inside a shipping container in a West Memphis field.

The Crittenden County Sheriff’s Office said they believe the woman found in the car died from asphyxiation due to carbon monoxide poisoning. The vehicle was still running when it was found.

Deputies said they don’t suspect foul play.

“Information gathered from family members concerning her mental and emotional state during her final communications along with facts gathered from the scene have led investigators to believe that Marilane Carter drove the vehicle into the container and in doing so caused her demise,” the sheriff’s office said in a news release.

Carter’s family said she’d been en route to Alabama to seek treatment for a mental health condition. She was last seen in the West Memphis, Arkansas area.

Deputies said they tracked parts of Carter’s drive to Rolla, Missouri where she stopped at a McDonald’s then she continued on to a hotel in West Plains, Missouri. She was at the hotel for over two hours before checking out, according to deputies.

Authorities said she then stopped at a convenience store in Hazen, Arkansas then traveled east to West Memphis where she was seen on gas station surveillance footage.

The mother of three talked several times with her husband and mother during her drive south. At one point, she appeared to be confused and disoriented on a drive her family said she’s taken many times.

“At one point Marilane mentioned to the family that she was traveling on dirt roads, going on a trek,” Carter’s brother-in-law, Brady McLaughlin, previously told NewsNation affiliate WDAF. “It should be interstate highways between two metropolitan areas, so that’s concerning and confusing.”

Carter’s family went to Arkansas last weekend to search for her but everyone returned home but her uncle, police said. Her uncle was driving and walking around the area where Carter’s phone last pinged when he came across three big shipping containers in a field, deputies said. One of the doors of a container was open and he found a car matching the description of Carter’s car in the container.

Carter’s family thanked volunteers for their support and help in a private Facebook group dedicated to finding her saying:

“These have been the longest weeks of our lives, as we tried to cling to hope that Marilane was still alive. Thank you to all who have offered words of encouragement, prayers, tips, help, and support during this very difficult time. We experienced firsthand the extreme love of friends and strangers. From a young woman who posted Marilane’s picture at truck stops all the way in Florida, to those who participated in prayer vigils, to those who volunteered to help us do a sonar search, the support has been amazing. Marilane was dearly loved by family and friends. The all-out effort to find her is a testimony to that”.

NewsNation affiliate WDAF contributed to this report.