In 1999 Monroe was ranked as the sixth greatest female star of all time by the American Film Institute. The official cause of Monroe's death was classified, by Dr. Thomas Noguchi of the Los Angeles County Coroners office, as "acute barbiturate poisoning," which he recorded as a "probable suicide." [116] Eight milligram percent of chloral hydrate and 4.5 milligram percent of Nembutal were found in her system after the autopsy. Her death was classified as "probable suicide," but because of a lack of evidence, investigators could not classify her death as suicide or homicide. Also, some conspiracy theories involve John and Robert Kennedy with her death, while other theories suggest CIA or mafia complicity. As a side note, toxicology tests revealed that Monroe also had a slight iron deficiency in her blood.