A former councillor was killed when he was attacked with a chainsaw and strangled over a "festering dispute" about the running of a charity farm, a court has heard.
Jonathan Stasiuk, 60, is accused of murdering 73-year-old Gerry White at the Lake Community Gardens on the Isle of Wight on 27 May.
Mr Stasiuk told a 999 operator "I have just murdered someone" following the attack, Southampton Crown Court heard.
Mr Stasiuk, of Sandown, denies murder.
The court was told he has pleaded guilty to manslaughter on the grounds of diminished responsibility.
Mr Stasiuk, a chef, had previously worked in pubs run by Mr White and they were both trustees of a charity farm project at the gardens, jurors heard.
Prosecutor Matthew Jewell QC said Mr Stasiuk developed an "entrenched hatred" of Mr White over "a number of grievances".
Mr Jewell said this included a belief that Mr White acted dishonestly over a £3,000 donation to the project from the Rotary Club.
He said Mr Stasiuk also thought Mr White was using the site as a "dumping ground" for items from his business and owed his partner £25.
On the day of the attack, Mr Stasiuk spotted Mr White walking in the gardens and proceeded to attack him with a chainsaw before it ran out of fuel, the jury heard.
He then "strangled and smothered" Mr White before having a drink "to calm himself down" and calling the police, Mr Jewell told the court.
The jury was told that when he dialled 999 about 20 minutes later, the operator asked if an ambulance was needed, to which Mr Stasiuk replied: "I'm going to make sure he doesn't."
Mr Jewell said the defendant then told the operator: "He's called Gerry White and I've just done him."
During police interviews Mr Stasiuk told officers he had used a chainsaw to give him "the edge" in the argument and was "glad" Mr White was dead, the court heard.
The trial continues.