A couple who allowed a neighbour to sleep on their sofa woke up to discover he had savagely murdered their four-year-old son.
Psychopath Anwar Daniel Rosser, who the couple treated as a friend, had asked to stay the night after turning up at their house after a night out.
But as the mum and step dad slept, the 33-year-old sneaked upstairs armed with four knives and stabbed Riley Turner to death.
On Wednesday, he was given a whole life sentence for the 'savage' and 'sadistic' murder of Riley.
The court heard that the former solider had stabbed the boy 30 times after Riley's mum Sharon Smith and her boyfriend Guy Earwaker allowed him to stay at her house in Keighley, West Yorkshire, on January 19, last year.
Riley's mum woke at around 4.30am and was horrified to find Rosser curled up in a ball next to her bed with four knives.
Riley was found semi-naked in his bedroom by his step-father who raised the alarm, while Rosser waited downstairs to 'hear the devastated reaction' of Riley's parents.
Paul Greaney QC, prosecuting, told Bradford Crown Court: "By any standard, the circumstances of the killing were appalling, involving a savage level of violence.
"The position of the prosecution is that the murder involved in sadistic motivation and that, furthermore, there was at the very least a strong sexual component to the killing."
Riley, who lived with his mum and stepfather along with his twin brother Mackenzie and baby brother Tyler, was described as an 'extremely happy, active and popular little boy who was particularly close to his twin brother'. He had spent the day before he died sledging with his family, the court heard.
On that day in January, Rosser - who lived opposite the family - had been drinking at the nearby Bracken Arms, where he 'drank a good deal'.
Then he, along with two women went back to Riley's parents' house. When the other women left, Rosser asked if he could stay because there were some men outside who he owed money to.
Sharon and Guy - who had treated him with 'considerable kindness' in the past and helped him to furnish his flat – 'took pity on him' and allowed him to sleep on their sofa downstairs.
But, Mr Greaney said: "It is clear that at some stage after Sharon Smith and Guy Earwaker had gone to their bed, the defendant climbed the staircase to the house, having armed himself with four knives (one of which he had brought to the house) and one other bladed article."
The prosecutor said that the cause of death was strangulation and stab wounds.
When Sharon woke and saw Rosser sitting next to her bed, she told him to get out, but he asked for some tobacco and 'said he was sorry', Mr Greaney told the court.
When Guy went to check that he had left, he noticed that Riley's bedroom light was on, he then found the boy.
Mr Greaney said: "Sharon Smith describes how she was screaming. Guy Earwaker then heard the front door slam. The defendant had been downstairs, obviously listening to their distress as they found and attempted to tend to their child."
Guy chased after Rosser, shouting threats. He returned to the house - and desperately carried the dead body of Riley to their next door neighbour's house, seeking help.
Paramedics took Riley to hospital but there was nothing to be done and the little boy was pronounced dead at 6am.
Rosser was discovered the next day when he had broken into a caravan, telling the man who found him: "I have ruined my life."
Rosser, who enlisted in the Army at the age of 16 but never saw active service, was described by experts as a 'psychopath' with 'alcoholic dependance syndrome'.
Sentencing Rosser, Mr Justice Coulson told him he had 'grossly breached the trust' of Riley's parents who showed him kindness and allowed him into their home.
A victim impact statement by Riley's mother Sharon, said: "I live every day in this nightmare. My son's never coming back because of that sick monster.
"I wish I had told that monster no that night when he asked if he could sleep.
"I didn't want him to get beaten up, but all along he had a knife in his pocket, plotting to hurt one of us, or all of us.
"I feel so much guilt that my poor son had to go through horrific things because of my kind heart. My kind heart cost me my son's life.
"I don't feel like ever being nice to people at all except my family. The guilt eats me away every day."
In a statement released after the case, Riley's family said: "While justice has now been done, no sentence will ever be enough for what we are going through and what that man has done to our family.
"It will not bring our little man back. Riley was always so happy and bubbly, caring and lovely. His twin brother misses him so much.
"We will never come to terms with what has happened and will always feel hurt at the way Riley was so cruelly and suddenly taken from us."