A man who screamed "I'll take your f****** head off" as he attacked police with a four-foot long sword in an attempt to help his arrested father escape has been jailed for more than four years.
Jamie Robertson, 22, had to be stopped by armed officers after he went on a rampage at his home in Ayrshire in south-west Scotland on August 2.
His 60-year-old father Ian was detained following a heated row between the pair.
But Robertson quickly became "extremely violent and aggressive", grabbing a pole, spade and then a huge sword to attack officers with.
He raised the sword above his head and warned they would get "done in" unless they let his father out of the police car.
Robertson slashed one officer - who prosecutors say remains traumatised by the attack.
After unsuccessfully attempting to stop Robertson with pepperspray, officers sought refuge behind the vehicle.
Video footage played in court showed Robertson smashing the windows of the police car and shouting: "Come on, hurry up. Run, dad...run."
The father and son then fled the scene as onlookers gathered.
Armed police caught up with the pair and managed to bring the stand-off to an end.
"Officers presented their weapons, aimed at Robertson and told him to drop the sword - he immediately complied," the court heard.
The injured officer has required counselling after suffering from nightmares and flashbacks.
The injury to his hand will "leave permanent scarring and impairment" and it is in doubt whether he will ever be able to regain full use of his thumb.
Robertson was sentenced to four years and four months after he admitted assault and behaving in a threatening manner.