Overview
On August 31, 1997, Diana, Princess of Wales, died following a high-speed car crash in the Pont de l'Alma tunnel in Paris. While official French and British investigations (Operation Paget) concluded the crash was an accident caused by an intoxicated driver and pursuing paparazzi, conspiracy theories remain prevalent.
The "Establishment" Plot
Mohamed Al-Fayed, father of Diana's companion Dodi Fayed (who also died), famously alleged that the couple was murdered by MI6 at the behest of Prince Philip. The purported motive was to prevent the mother of the future King from marrying a Muslim and potentially having a child with him.
Notable Anomalies
Theories often focus on the "mystery" white Fiat Uno that reportedly clipped the Mercedes, the alleged flashing light seen in the tunnel, and a letter Diana wrote to her butler, Paul Burrell, ten months prior, stating she believed someone was planning an "accident" in her car involving brake failure.