Eight South African policemen have been arrested on suspicion of murder after dragging a man tied to the back of a police truck through a Johannesburg street.
Mido Macia, 27, was found dead in detention with signs of head injuries and internal bleeding, according to an initial post-mortem report released by the IPID police watchdog.
An investigation was launched after a video recording emerged and was broadcast on television that showed the Mozambican taxi driver dragged behind a police vehicle.
The video showed Mr Macia scuffling with police, who subdue him. He is then bound to the back of a pick-up truck by his arms before the vehicle drives off in front of scores of witnesses.
Police told media they had detained the taxi driver after he parked illegally, creating a traffic jam, and then resisted arrest.
The incident is the latest in a series of scandals to hit the police force in South Africa, where more than 1,200 people a year die in police custody, Reuters reports.
The lead detective in the murder case against Olympic and Paralympic star Oscar Pistorius was removed from the investigation last week when it emerged he was facing seven attempted murder charges for allegedly opening fire on a minibus full of passengers.
Police shot dead 34 striking workers at a platinum mine in August last year - the deadliest security incident since apartheid ended in 1994.