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.
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The singer, 31, said on Twitter that she and her partner Jonathan Powell were grieving their loss.
A fine evening ahead to the south with some late sunshine in places.