Three volunteer police officers pursued a car before a passenger jumped out and ran into the path of a train, a watchdog said today.
The Metropolitan Police special constables are under investigation over the death of Mircea Adam at a level crossing in Enfield, north London, on Monday.
Mr Adam, 20, who was also known as Bobi Rostas, was killed after the patrol attempted to stop the Mercedes he was travelling in to check the driver was insured.
The Independent Police Complaints Commission (IPCC) said it will investigate whether the officers' actions were appropriate and whether national guidelines were followed.
The death raises the question of whether part-time volunteer constables should be allowed to drive police cars in emergency situations.
Last month Kent Deputy Chief Constable Adrian Leppard revealed more than 250 specials will be trained to answer "urgent duties".
One senior member of the Police Federation said it was a "step too far" and the officers could be a danger to the public.
Individual forces can choose whether special constables are trained and allowed to drive vehicles to respond to crimes or pursue suspects.
Some forces allow volunteers to drive cars only in routine situations, such as to attend non-emergency incidents, patrol or transport prisoners.
Essex Police guidelines state: "Special constables will not follow a vehicle which fails to stop as they will not be trained in initial phase pursuit."
The IPCC said the officers acted after carrying out a vehicle check on the silver CLK 230 Mercedes and pulling it over.
They activated the lights and siren of their marked vehicle when the driver got back inside and drove off.
The Mercedes pulled away from police before stopping at Enfield Lock level crossing where the barriers were down.
The driver and Mr Adam got out, hurdled the barrier and ran across the tracks. Mr Adam, of Rochestown, County Cork in Ireland, was hit by a northbound train and killed.
The other man narrowly escaped death and was arrested. A third man was also arrested. Both were aged in their early 20s.
The Metropolitan Police referred the case to the IPCC. CCTV footage shows the police vehicle was 20ft behind the Mercedes when the collision took place.
The pursuit is believed to have lasted for about 90 seconds several minutes earlier.
An IPCC spokesman said: "The IPCC has decided to independently investigate whether the actions of the officers were appropriate and whether Met and national pursuit policies were followed."Reuse content