Parents of Doctor Who Died of Cyanide Poisoning Say 'She Could Not Have Harmed Herself'

May 4, 2013— -- Investigators have not yet confirmed the cause of a death of a prominent Pennsylvania neurologist whose autopsy revealed she had "toxic levels of cyanide" in her system, but her parents spoke out against the possibility that their daughter's death was a suicide.

"We cannot imagine someone harming our daughter, but from what we're told, she could not have harmed herself," Dr. Autumn Marie Klein's parents, William and Lois Klein told ABC News in a prepared statement.

Klein, 41, collapsed at her home in Pittsburgh's Oakland neighborhood and later died on April 20 at UPMC Presbyterian Hospital, where she was chief of the division of women's neurology and an assistant professor of neurology, obstetrics and gynecology.

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The FBI is working to assist the Pittsburgh police in the investigation, but said suicide has not been ruled out as Klein's cause of death.

While authorities said Klein's husband, Dr. Robert Ferrante, was not named a suspect in his wife's death, police executed a search warrant overnight to case the couple's home, which they shared with their six-year-old daughter, Cianna.

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Investigators removed three vacuum cleaners, a computer tower, and even towed the couple's cars as neighbors still worked to process Klein's sudden death.

"We were stunned," Blithe Runsdorf told ABC's "Good Morning America." "I mean she was young, she was vibrant, she has a young daughter. We were just stunned."

Klein worked at UPMC Presbyterian Hospital. Her husband, Dr. Robert Ferrante, 64, is a professor of neurological surgery at University of Pittsburgh.

A private investigation into Klein's death has also been launched, with prominent forensic pathologist Dr. Cyrl Wecht at its helm.

"I have been privately retained, but I'm not able to give you any more information. But I have been privately consulted in this matter," Cyril Wecht told ABCNews.com when asked if he was retained by Dr. Robert Ferrante or his attorney.

Neither Ferrante nor his attorney responded to requests for comment.

ABC News' Christina Ng and Josh Margolin contributed to this report.