Chantal Sebire, 52, a former school teacher and mother of three, was suffering from an extremely rare form of cancer, which left her virtually blind, facially disfigured and in incredible pain.
She died at her home in the east of France last Wednesday only two days after a Dijon court had turned down her request to be given a lethal dose of barbiturates, ruling that it would contravene medical ethics and French law, which does not permit assisted suicide.
"Tests have shown the presence of a toxic concentration of the barbiturate 'Pentobarbital' in her blood," Dijon prosecutor Jean-Pierre Allachi said.
The prosecutor added that the concentration of barbiturates in her blood was three times higher than the medically-accepted lethal dose.
Barbiturates, normally prescribed for anxiety and insomnia, are not available in pharmacies.
Allachi said police were now investigating how Sebire was able to buy the drug.
Sebire suffered from cancer of the nasal cavity known as an esthesioneurblastoma, a condition so rare that in the past 20 years only 200 cases have been reported worldwide.
She was unable to take morphine for the pain due to the side effects.
Sebire's fight for the 'right to die' revived the euthanasia debate in France when before-and-after pictures of her face were reported in the media. She also made a televised appeal last month, where she said that children ran away from her in fright due to her horrific appearance.
She said in her TV appeal for the right to die that, "One would not allow an animal to go through what I have endured," and that she had "come to the end of what she could suffer."
Last week media reports said Sebire was considering going to Switzerland to take advantage of euthanasia laws in the country. However, her lawyer said the woman would not have survived the trip.
Euthanasia is only legal in the Netherlands and Belgium. Switzerland has a system which allows people to die in the country on the condition that the patients themselves apply the lethal dose.
