Kavan Brissett, aged 21, was stabbed on August 14, 2018 and died in hospital four days later but his attacker has never been traced.
Yesterday Kavan would have turned 24.
To mark the occasion, friends and family visited his grave to leave flowers, balloons and other tributes to the popular young man, who was a talented boxer.
His heartbroken mum, Emma Hamilton, paid tribute to him a Facebook post.
She said: “Miss you so much. Life isn’t the same without you here with us all.
"Three birthdays without you. It never gets easier only harder. You are missed and loved so much and forever.”
Kavan was knifed in his chest on the Grammar Street car park in Upperthorpe and was found collapsed on nearby Langsett Walk a short time later.
A man was caught on CCTV running away from the crime scene but has never been tracked down.
Four men were charged with conspiracy to commit robbery as part of the police investigation into the murder but so far nobody has been charged over Kavan’s death.
Detectives investigating the killing want to trace Ahmed Farrah, who is believed to hold vital information.
He was captured on CCTV at the Royal Hallamshire Hospital, where he was treated for facial injuries, on the same night that Kavan was stabbed.
He returned to the hospital the following day but then disappeared.
Farrah, who is also known as ‘Reggie’, was last seen in Cardiff the month after Kavan’s death but then went to ground.
His friends, relatives and acquaintances have all been visited and harbouring notices have been served, warning that anyone helping him evade arrest faces prosecution.
Farrah’s passport has never been found by police officers searching for him, so it is possible that he may now be abroad.
Anyone with information about the murder or Farrah’s whereabouts should call South Yorkshire Police on 101 and quote incident number 827 of August 14.
Crimestoppers can also be contacted on 0800 555111.