Atlanta (CNN) -- An 87-year-old Georgia woman, who was found dead in Lake Oconee 10 days after the discovery of her husband's headless body, appears to have been killed before being dumped in the lake. It's the latest twist in a grisly case that has baffled authorities.
Shirley Dermond did not drown but rather died from a "blunt impact injury to the head," Putnam County Coroner Gary McElhenney said Saturday.
The coroner's finding came a day after authorities pulled Dermond's body from the lake about 80 miles east of Atlanta.
McElhenney did not offer any further details about what might have been used to kill her before she was placed in the water or whether she suffered any additional trauma.
The decapitated body of her husband, 88-year-old Russell Dermond, was discovered May 6 in the garage of the couple's million-dollar waterfront home after friends went to check on them.
From the beginning, investigators treated Dermond's disappearance as an abduction. Her purse, cell phone and car were all still at home.
Authorities believe she was taken from her home after her husband was killed, sometime between May 2 and May 4.
Investigators continue to search for Russell Dermond's head, and they plan to look in the area where Shirley Dermond's body was found, Putnam County Sheriff Howard Sills has said.
Authorities were alerted by two fishermen who spotted what they believed to be a body in the lake, five or six miles from the couple's home.
CNN's AnneClaire Stapleton and Greg Botelho contributed to this report