Northumbria Police has confirmed the incident has been referred to the Independent Police Complaints Commission due to the contact between officers and the man before he died.
Officers were in the process of arresting a second man in connection with the disorder when the prisoner inside the police vehicle escaped and ran off from officers.
Enquiries were carried out to locate him and at 1:03am his body was found at the bottom of Marsden Grotto cliffs.
The air ambulance was called and the man was given CPR treatment by officers until paramedics arrived. Despite efforts to save him, he was pronounced dead at the scene. The area around the cliffs has been cordoned off while an investigation is carried out.
More top news
No-one was on board the single-decker vehicle, Humberside Police said.
The disgraced film producer has been the subject of an investigation in the US into allegations that he sexually assaulted numerous women.
Pyongyang said it is ‘willing to give the US time and opportunities’ to reconsider talks ‘at any time’.