A "habitual street robber" who stabbed a pizza delivery driver to death for his mobile phone has been told he must serve at least 23 years in prison.
Kasim Ahmed was 17 when he attacked Thavisha Lakindu Peiris, 25, who was working his last ever shift for Domino's Pizza before taking up his dream job as an IT consultant.
The teenager was on bail after breaching the conditions of a court sentence for a previous street robbery when he committed the murder, a judge was told.
Ahmed, now 18, admitted Mr Peiris's murder and was given a life sentence at Sheffield Crown Court today, along with his accomplice and cousin, Shamraze Khan, 26, who was found guilty of murder by a jury yesterday.
The judge, Mr Justice Coulson, said Khan played a secondary role in the attack in Sheffield last October but ordered him to serve a minimum of 24 years.
Ahmed and Khan, who at the time were both living at the same address in Southey Crescent, Sheffield, had robbed a teenager and her friend of mobile phones and cash just an hour before the killing of Mr Peiris.
The victim was from Sri Lanka and had come to the UK to complete a course at Sheffield Hallam University.
After graduating he was working up to 60 hours a week with Domino's to pay his family back for the expense of his studies before starting his new career.
Mr Peiris was attacked in the Southey area of Sheffield on October 27 last year after he had agreed to make one last delivery trip after complaining of being tired and wanting to go home.
He was stabbed a number of times by Ahmed after he resisted the attempt to steal his phone and, probably his satnav and cash too, the judge said.
Mr Justice Coulson said to Ahmed: "You don't like to be challenged. It's an affront to your self-esteem. So you stabbed him. You then decided to stab him again and again."
He noted that a pathologist found 14 different stab wounds on the victim's body, including serious injuries to his heart and neck.
"You brutally killed someone performing a form of public service just because you wanted his mobile phone," the judge said.
He said Ahmed's history of committing street robberies was "truly terrible for someone so young" and described him as a "habitual street robber who always carries a knife with him for that purpose".
The judge added: "It is not fanciful to conclude that in the light of your criminal history this was a murder that was waiting to happen."
He described Mr Peiris as an "exceptionally pleasant and likeable young man who worked hard and had a solid future in front of him as a software engineer."
The judge said to Ahmed: "It was that future that you took away from him."
He also read part of an impact statement from the victim's father in Sri Lanka which said: "Thavisha was one of the most caring and loving sons a parent could have.
"He was full of life and always had a smile on his face.
"Anyone who met him immediately liked him. He was bright, intelligent, hard-working and energetic."
The statement went on: "We are now left with nothing but broken hearts."
The judge said the statement went on to describe how the family had invested their entire retirement savings into their son's education and this is what he was working to restore.
Now, the judge said, his parents were left with no retirement income.
The judge gave them both life sentences.
He said he accepted it was Ahmed who wielded the knife and told him that his minimum term of 23 years would have been considerably longer if he had been an adult at the time of the killing.
The judge said father-of-four Khan was a "secondary party" but pointed out he was the older and more mature of the two killers.
Earlier, Robert Smith QC, prosecuting, explained how Ahmed was on bail at the time of the killing of Mr Peiris as he was due to be resentenced for failing to complete the terms of detention and training order given in respect of robberies and possessing a knife.
He had been remanded in custody because of this breach and only released on bail eight days before he killed Mr Peiris.
Mr Smith said Ahmed's record included convictions for possessing an offensive weapon, attempted robbery and robbery.
After today's hearing, Mr Peiris's family issued a statement which said: " We are still devastated and heartbroken over the loss of Thavisha and we are still unable to comprehend that he is actually gone.
"He gave us so many reasons to smile and was so caring and loving. All we have left are our memories, but they will never fill the void in our hearts. He will never again be with us and we will never hear his voice again.
"We sent our son to the UK to study so he could have a better life. We never thought he would be in any danger. The way in which he was taken from us is absolutely devastating, we cannot understand why anyone would do this to another human being and it fills us with such sadness."
The statement said: " While it doesn't bring our beloved Thavisha back, we now have some form of solace knowing they will be held to account for what they have done and they will be going to prison.
"We also want to offer our thanks to the public and the media for all of their kind words and support, it means so much to us knowing people cared about Thavisha and wanted to help find those responsible for his death. We cannot thank everyone enough.
"We would never want another family to go through such a tragic loss and endure the pain that we feel. Thavisha was the centre of our world and we will never get over losing him."
Detective Superintendant Lisa Ray, who lead the investigation, said: "Thavisha was a bright, intelligent and caring man who had worked hard to develop his career in Sheffield. His murder was an absolute tragedy and has caused untold grief for his mother, father and brother and for his many friends in Sri Lanka and in Sheffield.
"I would like to praise the family for the way they have conducted themselves in an extremely dignified way and for the way they have supported the investigation. Whilst nothing can fill the void or replace the loss of Thavisha, I hope his family can take some comfort knowing that justice has been served."
James Scott, district crown prosecutor, CPS Yorkshire and Humberside said: " Thavisha Peiris was a gentle and loving young man. He was working his last shift as a delivery driver in Sheffield before starting a new 'dream job' when his life was senselessly and brutally cut short, the victim of a frenzied knife attack. The loss of Thavisha has left his family and friends devastated."
Mr Scott said: "These two defendants will now be serving a total of 47 years in prison between them. We hope that this result brings some comfort to Thavisha's family and friends."