Media playback is unsupported on your device Media caption Aamir Siddiqi lived around the corner from the intended victim

Two "staggeringly incompetent" hitmen have been found guilty of stabbing to death an innocent student after the killers called at the wrong house.

Aamir Siddiqi, 17, was attacked at his Cardiff home by Jason Richards, 38, and Ben Hope, 39, in April 2010.

The killers, who will be sentenced next Friday, had been told to murder a different man on a neighbouring street.

The Swansea Crown Court jury returned its verdicts on the second day of deliberations.

We are pleased today that justice has finally been done and we can finally start to deal with the reality of losing Aamir Umbareen Siddiqi, Aamir's sister

Hope and Richards both denied murdering Aamir, and two separate counts of the attempted murder of his parents, but were convicted unanimously of all charges.

The killers showed no emotion as the verdict was delivered at the end of a four-and-a-half month trial. Aamir's family sat quietly in court.

After the verdict, Aamir's family spoke outside the court. One of his three sisters, Umbareen, said: "If he was still with us, he would be looking forward to turning 21 this year and completing his law degree.

"He was the heartbeat of our family."

She thanked police, Victim Support, all those who had tried to save Aamir, and the wider community in Cardiff for their help.

Image caption The killers mistakenly went to Ninian Road [l] instead of Shirley Road [r]

She added: "We are pleased today that justice has finally been done and we can finally start to deal with the reality of losing Aamir."

High on heroin

Aamir had run down the stairs to answer the door expecting to see his imam, who was due to give him a Koran lesson. Instead, he opened the front door in Ninian Road, Roath, to two masked killers high on heroin.

Hope and Richards wielded daggers over their heads and howled as they set upon the helpless A-level student.

Aamir's father likened the attackers' howling to the sort of noise made in martial arts when an attacker wants to terrify the victim.

The teenager desperately tried to run back into the house, but they chased him and repeatedly lashed out.

The execution of the bungled contract killing was described by the prosecution as an act of "staggering incompetence".

Media playback is unsupported on your device Media caption CCTV footage and mobile phone records helped officers build a case against Jason Richards and Ben Hope

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.

Mr Ahmad later recalled the terror which unfolded that Sunday and said he could not say how many times they had stabbed Aamir.

Saturated in blood

He told the police it all happened in seconds and Aamir "didn't say a single word". Police arrived at the scene, tried to save Aamir and administered CPR.

Sergeant Kee Wong told the trial the scene he found was the worst he had come across during his career. Aamir's T-shirt was saturated in blood and he counted several wounds on the teenager's body.

Det Sgt Stuart Wales also told the court it was "the most distressing incident" he had ever had to attend in 17 years of service.

Image caption Aamir opened the door of his Ninian Road home to his killers on a Sunday morning in 2010

"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.

It was an appalling end to what had begun as a "normal lazy Sunday morning", in the words of one of Aamir's sisters, Miriam, who had gone out to get him a takeaway.

The awful truth was that Aamir's killers 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.

But they went instead to a similar looking red brick, end-of-row house just around the corner in Ninian Road in the leafy suburb of Roath. The prosecution called it a colossal, fatal mistake for Aamir.

Blamed each other

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.

Media playback is unsupported on your device Media caption Aamir Siddiqi's parents, Iqbal and Parveen Ahmed, said he was a very popular boy who was liked by everybody

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.

Aamir's hopes of reading law at Cardiff University and then possibly pursuing a career in either the police or civil service ended in the most brutal fashion.

Aamir was a boy his parents called a gift and a blessing born after 17 years of marriage.

"This scene I will live with all of my life," Mrs Ahmad later told police.

Mr Ahmad said life had "lost its purpose" after the murder. His wife said: "Nothing is valuable now."