The death of Robert F Kennedy's 22-year-old granddaughter Saoirse Kennedy Hill was caused by an accidental overdose. A death certificate released on Friday revealed that Saoirse was found unresponsive at the Kennedy Compound back on August 1 due to a fatal mixture of prescription medications, methadone and alcohol. Among the prescription drugs found in her system were diazepam and nordiazepam (first marketed as Valium), fluoxetine (Prozac) and norfluoxetine (the anti-depressant Luoxetine). Her death came just one month before she was set to start her senior year at Boston College.