As John Williams answered a knock on his front door, he was faced with a hooded man who forced his way inside.
John, who was known as Jack, was later found tied up in his living room with head injuries - the result of a brutal attack where he was left to die in a pool of his own blood.
His murderer had fled the scene with some cannabis Jack had in an upstairs room.
Jack, 67, had been killed in his own home. His body was discovered when his former partner, Diane Ahern, forced her way into his flat in Pentrechwyth, Swansea, after he was not returning her phone calls.
Diane called the police but officers only had one clue when they arrived at the scene - a substantial amount of cannabis scattered around the property.
Cameras followed officers as they investigated Jack's death and the scenes are shown in the ITV show Code Blue: Murder.
In the programme, Detective Supt Richard Jones tells his team: "There's an awful lot to be done. I am sure the answer is out there. It's a category A, it's undetected and as things stand, we've got no suspects."
Killer who tied up pensioner and beat him to death jailed for at least 31 years
It's a neighbour that gives them their first lead when she mentions she saw a distinctively-dressed woman come to her door asking where Jack lived on the night he died.
The woman is then seen with two other men on another neighbour's CCTV camera coming out of Jack's house.
Suddenly, a detective recognises the woman - Gemma Owens.
Police then realise one of the men with her could be Jonathan Donne - a man well-known to police who had reportedly attacked other cannabis cultivators in their homes.
After the discovery of Jack's body, police recovered dozens of cannabis plants from the pensioner's loft, and a money box containing £10,000 in the kitchen.
There is now a motive. Donne, 42, went to the house to rob the pensioner of his crop of cannabis.
But after several raids across Swansea, Donne is still missing.
Simon Cairns, who owns a black Nissan Juke car in which Donne used to get to Jack’s house, is also arrested.
Armed officers prepare for a potentially dramatic take down at a house where Donne is reportedly holed up in on the outskirts of Swansea.
After a week spent on the run, Donne is found hiding in the attic of the house in the West Cross area and is arrested.
During a search of Donne's flat, a holdall containing ropes similar to that used to tie up Jack were found.
This, along with CCTV of Donne and DNA evidence, were used to convict him of murder.
At the time of the murder, Donne was on parole from prison.
In May 2008, a caretaker at a council block of flats in Swansea saw a trail of blood stretching down two floors.
At the same time an "agitated and crying" figure - who he would later know as Jonathan Donne - was seen walking down the stairs with another man.
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Spotting Donne's bloodstained hands, the caretaker immediately contacted the police.
When two officers arrived at the council flat in Griffith John Street in the city's Brynmelyn area they discovered the body of Michelle Harkett, Donne's partner who he had stabbed to death after a row over drugs.
After stabbing her in the chest, he had left her to die - but only after helping himself to a package of heroin she had concealed in her private parts.
Donne pleaded guilty to manslaughter and he was jailed indefinitley. Fast forward 10 years later and Donne is once again behind bars.
Donne was found guilty of Jack's murder and robbery and was jailed for a minimum of 31 years .
Ms Owens and Mr Cairns were later acquitted of all charges.
For Jack's niece, Emma Williams, his death was a day that would change her life.
"Mum came running in, she didn’t even need to say anything, and she said it was my uncle Jack.
"And I just knew something wasn’t right. I knew he had gone and I don’t know why. At that moment I didn’t know what to feel - it didn’t feel real."
"I'm angry," she said. "I'm really really angry.
"If he wasn't out then he wouldn't have been able to do that to my uncle. He'd still be here.
"He didn't want someone to break into his home and do that to him.
"He didn't want to die then.
"It's going to take a very long time to be able to fully move on."
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Jack's brother, David Williams, said: "He was such a big part of my life.
"We worked together for 20 years. He was my best friend, he was my confidant.
"The old saying is you don't realise what you've got until it's gone and that's very true.
"He's always in my mind and in my heart."
Code Blue: Murder airs on ITV1 tonight at 9pm.
