Body cams caught the horrifying moment a blood-soaked man was detained by cops after he 'almost decapitated' his victim.
In the footage, captured in Derby in August last year, PC Richard Edge can be seen directing a taser towards Martin McDermott, just moments after he had murdered Leslie Salmon, 44.
As PC Edge approaches the man he can be heard shouting: "Stand still, if you make any threats I will taser you.
"Turn around, walk forward, put your hands on that shed, stand still. If you make any threats to myself or others I will taser you, do you understand?"
He then adds: "I've got a red dot on you and I will taser you. Put your arms to the rear," before ordering his colleague to cuff McDermott, 60.
PC Edge managed to bring in the killer without the use of force and was given a bravery award for his actions.
He says he was called to reports of a stabbing at a bail hostel where he found the victim, arranged for medical help, and then went to look for the killer.
When the killer was apprehended and told that Salmon had died, he 'punched the air in delight' and told officers he was 'proud' of what he had done.
A court was told the grisly details of the case, including how McDermott had attempted to 'parade the victim's head' in what one detective called 'the most gruesome investigation I have led'.
Detective Inspector Gemma Booth of Derbyshire Police said: "The lack of remorse McDermott showed when we arrested him was simply shocking.
"When he was first arrested on suspicion of attempted murder at the scene he shouted, 'way hey'."
McDermott was jailed for life, to serve a minimum of 25 years, in February this year.
Sentencing, Judge Gregory Dickinson QC said: "You told the police you wanted to parade his head around on a pole through the hostel and when the prosecution outlined that element I noticed the wry grin that was on your face."
Speaking at the awards ceremony, Derbyshire Police Chief Constable Peter Goodman said: "Nights such as this are a truly humbling experience - showing the incredible work that is done by officers across the county.
"We have seen officers who have dealt with the most difficult and traumatic circumstances - to teams of officers who have worked hard to solve problems in communities - to detectives who have solved some of the most horrific crimes.
"I would like to say an enormous thank you to every officer for the hard work that they do day-in-day-out to keep the people of Derbyshire safe, and many congratulations to those who have won awards and been commended tonight.
"Nights like this make me so proud to be the Chief Constable of Derbyshire, and serve as a reminder to the level of dedication that our officers and staff show on every day."
Featured Image Credit: SWNS