Two "staggeringly incompetent" hitmen will be sentenced later for stabbing to death an innocent student after they targeted the wrong house.
Aamir Siddiqi, 17, was attacked at his Cardiff home by Jason Richards, 38, and Ben Hope, 39, in April 2010.
The pair had been paid £1,000 each to kill a different man on a neighbouring street.
A jury found them guilty of murder last Friday after a four-and-a-half month trial at Swansea Crown Court.
Hope and Richards both denied murdering Aamir and the attempted murder of his parents but were convicted unanimously of all charges.
The two men have already been told they will receive a life sentence, with judge, Mr Justice Royce, warning that he will set the "substantial" minimum term they must serve at a hearing on Friday at Swansea Crown Court.
During their trial, the court heard how Aamir had run down the stairs of the family home at Ninian Road in Roath, expecting to see his imam for a Koran lesson.
Instead, he was confronted by Richards and Hope, high on heroin and wearing masks.
They wielded daggers over their heads and howled as they set upon the helpless A-level student.
Aamir's parents frantically tried to help their only son. His mother, Parveen, leapt on the back of one of the attackers as he pursued Aamir in the dining room of their home.
His father, 68-year-old Sheikh Iqbal Ahmad, tried to pin the other against a wall using his head. Both were stabbed in the process.
Det Sgt Stuart Wales told the court it was "the most distressing incident" he had ever had to attend in 17 years of service.
"I saw the face of Aamir's mum, she looked absolutely traumatised," he said. "It is still an image quite clear in my mind."
Fellow officer Teresa Sullivan recalled her as inconsolable. "She just kept shouting 'My son, my son'. She wanted to see him," she said.
During the trial, the truth emerged that Aamir's killers had carried out a contract killing on the wrong victim, in the wrong house.
Richards and Hope had been paid by a businessman, angry over a collapsed property deal, to kill a father-of-four who lived in a neighbouring street.
After the murder, a huge manhunt began, and the killers' stolen Volvo car used in the crime was later found abandoned. Traces of Aamir's blood were found in the car's footwell, as were Hope's fingerprints and Richards' DNA.
After the killing the men were each paid £1,000 cash. Hope bought a pair of trainers and a laptop computer with the money.
Detectives pieced together the movements of both men before and after the killing by using the city's CCTV network and mobile phone evidence was also gathered.
Both men were arrested within days and immediately blamed each other for the killing. Hope told police he would not "take the rap" for something he did not do and drug addict Richards denied the killing.
But on the second day of deliberations, the jury rejected the killers' claims and convicted both men of the murder and attempted murders.