William Curtis, 70, was found guilty last month of sending threatening messages to the first minister and of sending or causing a threatening message to be sent to former MSP Stewart Stevenson in 2019 following a trial at the High Court in Glasgow.

He and Philip Mitchell, 60, were also found guilty of assaulting and abducting Sheriff Robert McDonald in a car park in Banff, Aberdeenshire, in June 2021, when Mitchell claimed he was performing a "citizen's arrest".

On Friday, Lord Weir said the pair were "entirely unrepentant" for their actions.

He jailed Curtis for 18 months for sending threatening messages.

He also jailed Curtis for a further four years and two months for the incident involving the sheriff, with the term to begin once the 18-month sentence has ended.

Mitchell was jailed for four years for the incident involving the sheriff.

During the trial, advocate depute Chris McKenna, prosecuting, read out a Facebook post from an account in the name of "William Patrick Curtis" that was flagged to Ms Sturgeon's office manager John Skinner in March 2019.

It said: "We have reason to believe while it is my intention to citizen's arrest her (Ms Sturgeon) to answer her treason, over the last three years, serious people who reel the abuse to the electorate by her criminal activities warrants assassination of her and several of her ministers, on down to even civilians who work in all agencies who have repeatedly lied to the electorate and conspired with the first minister."

Mr Skinner was asked in court what was made of the phrase "warrant assassination of her", and he told the jury: "To murder the first minister."

Threatening message sent with video linked to murder of Jo Cox

Curtis was found guilty of behaving in a threatening or abusive manner which was "likely to cause a reasonable person to suffer fear or alarm" by sending an email and posting messages on social media in which he made threatening remarks towards Ms Sturgeon on various occasions between 27 February and 6 March 2019, as well as another charge of posting abusive material online about two other people in October 2020.

He was also found guilty of sending or causing a threatening message to be sent to Mr Stevenson on 9 March 2019.

It had a link to a video relating to the murder of West Yorkshire MP Jo Cox.

The court heard a direct message was sent on Facebook to Mr Stevenson from a person called "Carole Curtis" which read: "Your turn is coming of that you can be sure."

On Friday, advocate Chris Miller, representing Curtis, told the sentencing hearing at the High Court in Glasgow that his client maintains his position that the messages to Ms Sturgeon and the others were not threatening and abusive to the extent a reasonable person would suffer alarm.

During the 11-minute hearing, Mr Miller also told the court his client maintains he did not send the message to Mr Stevenson.

'Personal vendetta against those in authority'

Curtis listened silently as Lord Weir told him it appeared he had a personal vendetta against those in authority, and he showed "complete disregard" to the likely impact of the posts.

Paul Mullen, representing Mitchell, told the court his client was "completely down a rabbit hole where he has simply not seen the wrongfulness of his actions" and he still believes targeting the sheriff was "legitimate".

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Lord Weir told Mitchell it must have been a "frightening and humiliating" experience for the sheriff, and told the offender: "What you did was not only an assault on Sheriff McDonald, it was an assault on the rule of law."

Curtis and Mitchell had their sentences backdated to the point they entered custody.

All of the offences occurred in Aberdeenshire.