A man shot in the neck got into his car and attempted to drive home after the shooting, a jury heard.
But Gary Morgan, who was killed near his home at Danesbrook Farm, Stanton St John, made it less than 40 metres back up the country lane before losing consciousness.
He was found in his car in a ditch by his wife Helen, after she was told he had failed to arrive at work.
Mrs Morgan's ex-husband, Allan Kimber, 41, of Stert Street, Abingdon, denies murdering Mr Morgan.
At Oxford Crown Court yesterday, Pc Mark Howard, who attended the scene on October 17 last year, told the jury that Mr Morgan was "soaked in his own blood".
He added: "From the blood patterns on the car's steering wheel it is likely that he was shot while the car was facing forwards and the evidence shows that he tried to reverse his car up the track. It is likely he lost consciousness at the time the car went into the ditch."
Opening the prosecution case on Tuesday, Neil Moore told the jury: "No one knows precisely what happened in the last few moments of Gary Morgan's life, no one apart from his killer.
"We know the car stopped no less than 40 metres from the gate where he was probably shot in the neck.
"He probably began to get out of his car, was shot in the driver's seat or close proximity to it. Having been shot, he then tried to flee by reversing the car back up the lane towards the farm. He eventually lost control of the vehicle as he perhaps began to lose consciousness."
Emergency services initially thought Mr Morgan had died in a car crash, but yesterday, the jury heard that ambulance staff had suspicions.
John Willis, of Oxfordshire Ambulance Service, said: "I thought it was very unusual. The car appeared to be reversed in a ditch with very minimal damage. For the amount of blood that was in the vehicle it did not seem to be consistent with what I had seen in my experience of other road traffic accidents.
"When I saw Mr Morgan there was a lot of blood - on his chest, face, steering wheel and splatters of blood on the inside of the windscreen.
"There was also a large pool of blood between his legs on the seat and a pool of blood on the footwell behind the driver's seat."
A post mortem showed a bullet in Mr Morgan's neck had caused fatal damage to a major artery.
Mr Moore said: "There is no doubt that Gary Morgan was killed as a result of being shot despite it not being spotted at the time of death. Someone was lying in wait for Gary Morgan in the middle of the night, someone armed with a weapon ready to ambush him as he made his way to work."
Mr Morgan worked at a bakery in Bicester. He had previously worked as a bus driver for Stagecoach, which also employed Mrs Morgan and Mr Kimber.
The case continues.
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