The IOPC's initial investigation has established that the driver of the Honda Accord was reported for failing to stop for police at 1.42am, and police had concerns about the way in which the car was being driven.
Modecai Juma, 51, had previously failed to stop for officers, and a police pursuit began at 3.24am, the IOPC said in a statement.
The Independent Office for Police Conduct (IOPC) has now launched an independent investigation into the involvement of South Wales Police.
The police watchdog has started an investigation into a police chase, which began minutes before a fatal crash.
The IOPC's deputy director of investigations, Catherine Bates, said the watchdog's thoughts were with Mr Juma's family and it would "continue to update them" as its enquiries progressed.
