The car that was involved in a fatal crash when it was driven the wrong way down the M40 motorway was involved in another collision five days earlier, police said.
Witnesses claimed the Subaru Forester, which was towing the caravan, was driving at up to 60mph along the motorway's northbound carriageway on 15 October.
Due to "previous police contact" the force has referred itself to the Independent Office for Police Conduct (IOPC) in relation to the second, fatal collision.
Five days later the force again received reports about the vehicle, before the car collided with a Ford Mondeo and a Ford Focus, near junction 6 on the motorway.
The driver of the Subaru and the passenger, both in their eighties, both died. They are yet to be formally identified.
Stuart Richards, a 32-year-old from Cheshire who was driving the Ford Mondeo, also died and was identified by police yesterday.
The carriageway was closed as emergency services attended the scene and was re-opened on Tuesday morning.
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