Gary Dean was found shot in the back with an airgun and had also been beaten with a rock and branches.
Carol Dawson, 71, of Stonewood Grove, Hoyland, and Scott Dawson, 41, of Allotts Court, Birdwell, were charged with his murder and are now on trial at Sheffield Crown Court.
The pair deny playing any role in the 48-year-old’s death after his body was found by a walker in a ditch off Moorend Lane, Silkstone Common, on September 6 last year when his mobile phone’s ringtone sounded - a call made by his worried wife, Caroline.
The court was told on Tuesday that the Dawsons - who owned 27 acres of nearby land - were involved in a long-running dispute relating to Mr Dean’s behaviour when he was running and cycling on a public right of way which cut through their fields.
Keen sportsman Mr Dean, who completed the London Marathon 18 times, had been the subject of multiple complaints lodged by the Dawsons to police for alleged fly-tipping and arson incidents, although there were no convictions.
Prosecutor Peter Moulson QC said: “This killing was planned and Mr Dean was attacked in a field owned by the Dawsons between 6.50am and 7.20am on September 6, 2018.
“We submit that there was a vendetta against Mr Dean and the family took matters into their own hands - they blamed him for causing them problems on their land.
“Mr Dean’s wife, Caroline, last saw him when she left for work on the morning of the murder. She noticed a Volkswagen Tiguan, which we say was owned by Carol Dawson, parked in a lay-by on House Carr Lane, and was effectively acting as a lookout to confirm her departure.
“Mr Dean habitually took a route which included a field owned by the Dawsons while enjoying his hobbies. Shortly after his wife went to work, Mr Dean - who was unemployed and a man of routine - also left the terraced cottage they shared.
“At 1pm, his wife attempted to call him and had no reply, nor did she on any of the other occasions in which she tried to make contact during the afternoon.
“His phone was switched on, it was audible, and this led a member of the public to find his dead body at about 5.30pm as it was ringing.
“An air rifle had been purchased by Scott Dawson and a pellet was lodged in Mr Dean’s back between two vertebrae.
“Although it’s very possible this was not fatal, other makeshift weapons were used in the deadly attack including a rock, which was found with blood stains, and branches.
“It’s not possible to order which of these attacks occurred first because they took place on a rural field, away from any CCTV and prying eyes.
“However, what we do submit is that Mr Dean was first assaulted in the Dawsons’ field and attempted to escape. High concentrations of dirt on his knees and hands suggest he scrabbled on all fours before he was killed and dumped in the ditch.”
The prosecutor told the jury about an incident, which took place in 2016, which resulted in the Dean family’s car and house being daubed with painted messages saying ’STAY AWAY’ and ‘PAEDO’.
“There was never any complaint, none of any sort, about Mr Dean lodged with the police with regards to paedophilia,” Mr Moulson added.
“He did not have a criminal record but the vendetta even resulted in Carol Dawson writing to Mr Dean’s wife’s school, where she served as a headteacher, about the allegations.”
A recording of a telephone conversation between the Dawsons and the police was played to the jury, which heard an angry exchange in which Scott Dawson told the answering officer that he would ‘rip him (Mr Dean) in f***ing half’ due to the police’s ‘failure to act on reports’ about Mr Dean’s alleged behaviour on his land.
In the conversation, Carol Dawson said: “We won’t keep standing for it. The police have not been there for us and he’s doing what he wants, causing damage to our land. It’s just not good enough.”
The trial, which is expected to last for five weeks, continues.
Victim’s widow: ‘It’s hard to comprehend’
A BARNSLEY headteacher - whose husband was killed in brutal assault - told a jury the couple had received letters saying ‘men were going to sort him out’ before he was found dead.
Gary Dean, of Moorend Lane, Silkstone Common, was found in a ditch on September 6 last year.
The 48-year-old’s alleged killers, mother and son Carol Dawson, 71, and 41-year-old Scott Dawson, have been appearing at Sheffield Crown Court .
Gary’s wife, Caroline, headteacher of Hunningley Primary School, told a jury that the couple had been subjected to a torrent of abuse since 2016 and claimed it stemmed from her husband’s long-running dispute with Scott Dawson, a local landowner.
Gary, who was unemployed, was said to be on the autistic spectrum and had been the subject of tests before his death, the court heard.
The dispute, the Dawsons’ defence team say, related to Mr Dean’s behaviour when he was on their land - they allege that he defecated on paths, started fires, placed barbed wire at horse riders’ height and put scarecrows in fields without permission.
“I knew there had been issues between Gary and the Dawsons,” Caroline said.
“Our car and house were both vandalised, our home was broken into and we were assaulted. We also received letters stating that eight men were ‘going to sort Gary out’.
“He used to place scarecrows in the Dawsons’ land but never meant any harm by it, but I remember thinking that it was a massive leap going from something so trivial to the revenge attacks.
“Gary was a quirky man, eccentric, but wouldn’t ever want to harm anyone. He was a complex character.
“He had many friends and his death shocked and saddened so many people beyond his immediate family.
“No-one can comprehend why anyone would do this.
“I am haunted by the fact that the last moments of Gary’s life were so brutal and violent - no-one deserves to die like this, particularly in a place where they found so much peace.”