Scott Guy died within seconds of being shot in the throat at close range, leaving his body riddled with hundreds of shotgun pellets.
But the forensic pathologist who carried out the post-mortem examination told the High Court at Wellington today that he could not say for certain if Mr Guy was shot more than once.
Ewen Macdonald's murder trial was today dedicated to evidence on the forensic work carried out after his brother-in-law, Mr Guy, was gunned down in the driveway of his Feilding home on July 8, 2010.
Macdonald, 32, has denied murdering Mr Guy, 31, after growing tensions over the family farm they co-managed.
Forensic pathologist Dr John Rutherford told the court Mr Guy died from a 13cm by 5cm shotgun wound to his neck, which extended from the left of his chin to the right of his voicebox.
The shotgun pellets entered Mr Guy's neck horizontally from the left, in an upwards direction.
They fractured part of his jaw, sending bone fragments into the surrounding tissue, and severed the carotid artery that supplies blood to the brain.
An x-ray showed pellets passed through the roof of his mouth, through the back of his eye socket and into his brain.
Some 258 to 260 shotgun pellets were found in Mr Guy's body. Plastic shotgun wadding was also found in his throat.
Dr Rutherford said pellet injuries were also found on Mr Guy's left hand and forearm, which could be explained by Mr Guy raising his arm to his face.
There were no other external injuries.
Under cross-examination from defence lawyer Greg King, Dr Rutherford said it was his opinion that all the injuries could be explained by one shotgun discharge.
However, he could not exclude two or even three discharges.
Dr Rutherford said there were no specific pellet patterns for him to distinguish how many shots were fired.
A post-mortem examination alone could not determine how many shots were fired, and other evidence was needed.
Dr Rutherford was also unable to say for certain how quickly Mr Guy died, but due to the damage to the carotid artery it would be "within a matter of seconds".
There were no powder burns or contact wounds, which meant the killer was not extremely close.
"We're looking from many centimetres to a few metres, I would guess."
ESR forensic scientist David Neale examined the murder scene on the day Mr Guy died and found pooled blood around the top of his body.
The blood had begun to flow into a footwear impression near Mr Guy's head and under part of the driveway gate.
A cap found in blood near Mr Guy's head had numerous areas of damage to its peak, possibly from a shotgun.
The court earlier heard evidence on the shoes worn by Mr Guy's killer, which have never been found.
The Crown alleges Macdonald wore size nine Proline dive boots with a distinctive wavy pattern when he ambushed Mr Guy at the bottom of his driveway as he left to do the morning milking.
Mr Neale said all the wavy-patterned footwear impressions at the murder scene had come from the same boot, which he concluded was a Proline W375 neoprene dive boot or similar.
He said the shoes worn at the scene were size nine or 10, as measured by the forefoot of the impressions.
But under cross-examination by Mr King, he agreed the size nine boot he had seen as an example could not have been the same as those worn at the scene.
Mr Neale said he counted about 32 to 33 rows of the wavy pattern on the forefoot of three partial footwear impressions at the scene.
But under instruction from Mr King, he counted about 29 rows on the forefoot of a size nine Proline boot produced as an exhibit in court.
Referring to the impressions at the crime scene, Mr King said: "If your calculation is accurate, there is no way in the world that it can be a pair of size nine Proline boots."
Mr Neale agreed the size nine example boot he had seen did not have 32 to 33 rows of waves.
He said discounting the number of waves, the impressions at the scene matched a Proline boot, or a boot that closely matched it.
Raising his voice, Mr King asked: "Why would you discount the rows of waves?"
Mr Neale said the impressions at the scene were from a boot he had not seen, and may or may not have been from a Proline boot.
He said he had seen only one example of each size of boot.
Mr Neale agreed the boot could be from a "rogue batch" or may not be from a Proline boot at all.
The trial before Justice Simon France and a jury of 11 continues tomorrow with more forensic evidence.
