THE shotgun used by an "ungrateful son" to kill his elderly parents was stolen in a North-East house burglary, a court heard.
Peter Wright QC, prosecuting, said two calls were made from Stephen Seddon's mobile telephone that day to a man named Brian Jopper, from Darlington.
Jopper is a man with criminal convictions for serious offences, including firearms, he added.
''Somebody had to get a firearm in order to dispatch the parents of this man."
Manchester Crown Court heard it had been stolen in a "professional burglary" at the home of Dennis Dolphin in the Crook area of County Durham on New Year's Eve 2011 - before it was sawn off to aid concealment.
Mr Wright said it was a ''remarkable coincidence'' that the gun used to kill the Seddons in their home in Sale, Greater Manchester, was stolen in the North-East where their son lived.
Stephen Seddon, also known as Nic, of Benevente Street, Seaham, denies two counts of murder on July 4 last year and two counts of attempted murder on March 20.
The jury heard Robert Seddon told his doctor he now believed his son had previously tried to kill him the day before he was shot dead.
The couple survived after the hired car Stephen Seddon was driving veered off the road into a Manchester canal.
''He had previously expressed a view the canal incident was an accident,'' Mr Wright said. ''By this time he was expressing his concerns to his GP that his son had tried to kill himself and his wife."
The retired British Airways worker and his wife - described as a quiet and caring - had already given their son £40,000 cash and bought his Seaham home to keep a roof over his head.
But they ''had to die'' because the father-of-three, who lost his job in October 2011, stood to inherit everything in their wills, the court heard.
The day after the doctor's appointment, at around 5.30am on July 4, Stephen Seddon left wife Nicola Stockton and their children at the static caravan which his father allowed him to use for holidays in Fleetwood, Lancashire.
Seddon returned to Seaham in his VW Passat to sign on before borrowing a BMW from brother-in-law, Robert Stockton Junior.
The car was traced by police Automatic Number Plate Recognition systems, and CCTV cameras, travelling to the North West.
At 1.33pm it was seen on CCTV near his parents' home and 26 minutes later it left, said Mr Wright.
The Seddon's daughter, Lesley, died aged 40, and the couple looked after her son Daniel, 17, who has learning difficulties.
His carer raised the alarm on July 6 when, returning Daniel from respite care, he failed to get an answer. Peering through a window, he saw Mr Seddon's body on a sofa.
Police found the shotgun in Mr Seddon's lap with his right hand resting on the weapon.
But this could not have been a murder-suicide as the killer wanted police to believe, the jury heard.
''The ballistic evidence in this case is entirely inconsistent with that having taken place,'' Mr Wright said.
He added the killer had fired the left-hand barrel, reloaded, fired it again and left an undischarged cartridge in the right-hand barrel.
Mr Wright suggested the killer may have been expecting three people in the house, though Daniel was away with his carers at the time.
After Stephen Seddon allegedly shot his parents, he returned to Seaham around 4.30pm and met Lee Stockton at a retail park where Mr Stockton went to a bookmakers and the defendant bought drinks.
Soon after he returned to his family at the Fleetwood caravan park.
The trial continues.
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