Former Bathurst mayor Robert "Bobby" Bourke has been found guilty of misconduct in public office for his role in the attempted blackmail of another councillor.
The charges arose from his role in helping to deliver an anonymous letter to fellow councillor Jacqui Rudge in March 2020.
He did not respond when the verdict was read out and he will be sentenced in September.
Earlier in the trial the court heard Ms Rudge received an anonymous letter that threatened to reveal her mental health issues unless she stood down from council.
"We recommend you stand down and seek professional help," the letter, which was tendered to the court as evidence, read.
"Written in confidence however if not acted on in the next seven days this will be made public."
The court had previously heard Ms Rudge felt suicidal the day she received the message.
During the trial, the jury heard another man, Bathurst businessman Darryl Leahey, had admitted to writing the letter but Mr Bourke facilitated its delivery.
In two police interviews played to the court as evidence, Bourke maintained he did not know the contents of the letter he helped to deliver for Mr Leahey.
Crown prosecutor Paul Kerr told the court the two men were in a joint criminal enterprise and "hatched a plan" that amounted to an attempt to "undermine the democratic system of local government".
In his closing address Mr Kerr said it was "inconceivable" that Bourke did not know the contents of the letter he was helping to send.
"[It] flies in the face of common sense that the mayor would not have read the document between the time it was passed to him and the time it was posted," he said.
Mr Kerr also questioned why Bourke asked someone else to purchase the envelope, and a second person to address and post it, if he had no idea what the contents of the letter were.
"Why did he not want to have anything to do with the letter? What did he know about the letter before it was sent?" Mr Kerr said.
"You would not go to all of this trouble if you believed that the letter was purely innocent."
The defence admitted during the trial that the letter was "nasty" but asked the jury to consider whether it constituted blackmail or was "just politics".
"What it says is nasty, the defence is not hiding from that," defence lawyer Peter Skinner said.
Before the verdict, Mr Skinner had told the court the Crown case was circumstantial and left a "reasonable doubt" that his client did not know the contents of the letter.
"It is not a crime to not ask why someone is asking you to post something that you haven't read the contents of," he said.
"Ultimately, you'd have to have a reasonable doubt in this case."
