Channel 4 has commissioned a four-part series from Sandpaper Films to tell for the first time the full story of two police investigations into the death of Princess Diana, one by the French Brigade Criminelle in 1997, one by the Metropolitan Police in 2004. Princess Diana's death in a car crash in 1997 shocked the world and ignited a debate about how and why she died. With exclusive access to the top detectives on both sides of the channel - most of whom are speaking for the first time - Investigating Diana: Death in Paris will explore how both investigations grappled to separate fact from speculation. The series will hear how detectives chased every lead while manoeuvring between unreliable witnesses and fallible memories. It will also examine the public's insatiable demand for answers, which fuelled unprecedented press interest and the proliferation of online chatrooms, where speculation on the 'real cause' of Diana's death became one of the first viral sensations of the early internet. Told as a gripping and forensic police procedural, the series will explore how powerful individuals, the press and the internet created and fuelled conspiracy theories that overwhelmed facts and called into question the very nature of truth.