Atlanta, Georgia (CNN) -- A Georgia inmate, found dead in prison where she was serving a life sentence for killing her boyfriend and husband with antifreeze, apparently committed suicide, authorities said Wednesday.
Autopsy results on Julia Lynn Womack Turner showed she died from the "toxic effects of the prescription medication propranolol, a blood pressure medication that Ms. Turner had been prescribed," according to Georgia's chief medical examiner.
Investigators found no evidence of injury or foul play and the prison death is being classified as a suicide, Dr. Kris Sperry said.
"Toxicology studies revealed that Ms. Turner had a lethal level of this drug in her blood indicating that she had ingested an amount well above the prescribed dosage," Dr. Sperry said.
Turner, who went by Lynn, was serving a sentence of life in prison without parole in the Metro State Prison for women in Atlanta. She was found unresponsive in her cell on the morning of August 30, and medics could not revive her.
Lynn Turner was convicted of murder in the deaths of her husband, police officer Glenn Turner, and her boyfriend, firefighter Randy Thompson. Both men were poisoned with antifreeze. Glenn Turner died March 3, 1995, from what was initially thought to be an irregular heartbeat. A week later, Lynn Turner moved in with Thompson, with whom she had begun an affair several months earlier.
But it was not until Thompson died in 2001 under similar circumstances that authorities exhumed the body of Glenn Turner and performed another autopsy.
In both cases, the men had exhibited flu-like symptoms before being taken to the emergency room. They both died less than 24 hours after they left the hospital, from what a coroner initially identified as heart failure. Further examination, however, revealed traces of ethylene glycol, a byproduct of antifreeze, in both of their bodies.
Lynn Turner was convicted of killing her husband in 2004, then convicted in 2007 of killing Thompson.
Cobb County, Georgia, prosecutors labeled her a "black widow" who murdered both men for financial gain. After her husband's death, Lynn Turner received more than $150,000 in benefits and interest from his life insurance and pension. She received about $36,000 in benefits as a result of Thompson's death.
CNN's Ashley Hayes contributed to this report.