Police believe Sam Parker dumped his estranged wife's body behind a cornfield in Chattooga County 3 1/2 years ago, but even after the autopsy they can't tell how she died.

"You've got to take into account [Theresa Parker's] body was out in the elements for 3 1/2 years, subjected to many circumstances," Walker County, Ga., Sheriff Steve Wilson said Friday.

The Georgia Bureau of Investigation announced Friday a medical examination showed Theresa Parker, a former Walker County 911 dispatcher, was a homicide victim. But the exam could not reveal what specific injury caused her death, GBI spokesman John Bankhead said.

"It's rare to determine the cause of death when you have a skeleton that's been out in the woods this long," he said.

Earlier this week, Chattooga County Sheriff John Everett said Theresa Parker's skull appeared to have a hole in it. Bankhead said it was not a bullet hole.

Her husband, Sam Parker, was convicted of murder last year even though her body had not been found.

Investigators don't think the new findings will help Sam Parker in the appeal that he filed shortly after he was convicted.

"It doesn't change the verdict at all," Wilson said.

Sam Parker, a former LaFayette, Ga., police officer, was sentenced to life in prison and is housed at the Georgia State Prison in Reidsville.

His attorney, public defender David Dunn, could not be reached Friday for comment.

A farmer found Theresa Parker's jawbone in a dry creek bed last week. The rest of her remains were found nearby.

Bankhead said an anthropologist and Chief Medical Examiner Dr. Kris Sperry examined her bones earlier this week at the GBI Crime Lab in Atlanta.

Based on the exam, the investigation and the circumstances surrounding Theresa Parker's disappearance, Dr. Sperry classified her death as a homicide, he said in a news release.

The remains were taken to the South Crest Chapel of Lane Funeral Home on Friday where the family will plan a service, said her sister, Hilda Wilson.

"I'm just trying to make the arrangements," she said.