Dad-of-two Matthew Farmer was jailed for life after he stabbed his estranged partner 21 times and tried to strangle her after lying in wait in her garden.
His sentence for murder was life imprisonment with a minimum tariff of 29 years to serve before a parole application can be considered.
For the officer in the case, Detective Inspector Rebecca Hodgman, of Nottinghamshire Police, there really are no words to describe what Farmer did to Stacey Clay, a 39-year-old mother-of-four who had broken off her relationship with him.
Farmer repeatedly contacted Miss Clay after the break-up and harassed her before hiding behind a barbecue in her garden and launching the knife attack when she went outside for a cigarette.
In an interview after the verdict, dedicated DI Hodgman said of Farmer's actions: "It was horrific. Matthew clearly demonstrated a mind-set of, ‘if I can’t have you, nobody will’.
"This brutal attack was committed in daylight, while their children were present in the house. He had no regard for them, no regard for what they may witness and no regard for them losing their parents.
"This appeared to be a pre-planned attack which was extremely violent. Matthew showed a clear determination to stop at nothing to kill her.
"After stabbing her so many times and with that much force that the knife snapped, he went on to strangle her. Matthew was only stopped when he was tasered".
Brave officers PC Jake Allchurch, who received a judge's commendation for his actions, and PC Zoe East, were the first officers on the scene as 42-year-old Farmer, of Logan Street, Bulwell, was holding Miss Clay down on the grass after knifing her.
PC Allchurch, who is no longer a police officer due to the incident, told the court he is five feet and five inches tall and weighed nearly nine stone.
He took on Farmer, who was much bigger than him, when he saw the accused on top of Miss Clay in her back garden in Andover Road, Bestwood.
PC Allchurch had told the jury at Farmer's Nottingham Crown Court trial: "There was blood everywhere. She (Miss Clay) was unresponsive. Her eyes were open".
The courageous officer shouted at ex-doorman Farmer to "get off her" and ran over and tried to grab him off her. PC East then moved in and tasered Farmer who was cuffed and taken into custody.
DI Hodgman said: "Those officers did risk their lives, they were very brave in their actions.
"They disregarded their own safety in an attempt to detain Farmer and give immediate first aid to Stacey.
"Police officers deal with some of the worst situations day after day, facing things that other people probably wouldn’t experience in a lifetime. I’m sure these events will have a lasting negative effect on them for as long as they live".
The police investigation relied heavily on CCTV - not only from Miss Clay's home - where a motion-activated camera she had installed for her own safety had filmed Farmer's manic knife attack in high definition on her.
This graphic footage was played to the jury, as well as footage of Farmer prowling around outside her house late a night.
Clear footage was seized of him buying the murder weapon - a small knife from Tesco Extra, Bulwell, where he worked as a security guard for more than eight years, and of him stabbing the knife into its packaging on the store's security desk just hours before.
After the attack, which claimed Miss Clay's life two weeks later, on June 2, in hospital, Farmer had seemed pleased with himself, the court heard, and smirked and winked to officers.
He exercised his right to make no comment in police interview as Miss Clay remained, at that time, in intensive care.
John Cammegh QC, prosecuting, had told the jury at Farmer's trial, where he denied Miss Clay's murder, that the case relied heavily on CCTV, and "CCTV of the attack is pertinent and, regrettably, I have no alternative to play it to you".
DI Hodgman said: "This is a tragic and devastating incident where a woman lost her life, children lost their mother, family lost their relative and all that knew her lost a loved one.
"There was no doubt on who killed Stacey but Matthew still pleaded not guilty. I know none of this will bring Stacey back, however, I welcomed the guilty verdict and the 29-year sentence".
Miss Clay has wanted to move on with her life but Farmer didn’t allow her to do this, she added. "He made her feel vulnerable, scared and intimidated".
DI Hodgman has been on the Major Crime Unit for over four years, and a senior investigating officer for a large number of murder investigations, all of which have their own difficulties in different ways.
She adds: "The most harrowing part of this investigation was the clear CCTV with sound. Whilst this provided invaluable evidence, myself and investigators have watched and studied what Stacey went through numerous times, the footage of which will remain with us all".
* Farmer, who had a history of taking overdoses, is understood to have taken an "overdose of tablets" after he was convicted by the jury. He was sentenced in his absence on Friday, January 21.
A Ministry and Justice spokesman said on Friday, January 28 that he is still being treated in hospital.
