Auckley man Kieran Walker, 23, was found guilty of the murder of Jordan O’Brien, 25, in Gainsborough in March last year and was jailed for a minimum of 28 years for the attack.
But the driver of a BMW believed to be connected to the murder has never been traced – and Jordan’s family have called for help in tracing the motorist.
Heartbroken sister Lindsey Denman told Lincolnshire Live: “In my opinion he is as much at fault as Kieran Walker. I honestly believe this driver has as much blood on his hands as Kieran does.
“He could have actually stopped him that night. He would have seen him with a machete.
“It’s a little town and people talk. I just want someone to have the decency to say who it is. There are people out there who know who did this.”
Jordan was savagely killed with a machete after he was attacked in Scampton Way, Gainsborough by Walker of Larch Avenue, Doncaster due to a grudge over a £2,000 drug debt.
Doctors amputated one of his legs in a desperate bid to save him, but he died in hospital on April 1 with his devastated family by his side.
The 34-year-old mum-of-three says she nor Jordan’s other relatives won’t stop until the man is caught.
“My family and I aren’t going to rest until this person is brought to justice - even if it means sharing the post [the police appeal] every day.
“We don’t want to see Kieran’s smirking face but if we have to share it every day to get people to recognise him then we will.”
She added: "While I’ve got breath in my body I will never give up on this. I want justice for my little brother and for my mum for her son."
After the court case last year, Detective Inspector Andy McWatt, investigating officer, said: “I am satisfied that the verdict has brought some justice to Jordan’s family, but of course it will never bring him back.
“Jordan has been cruelly snatched away from his loved ones by the calculating murder committed by Walker.
“I cannot imagine what thoughts were going through Walker’s mind when he carried out this attack.
“I cannot thank Jordan’s family enough for their support and the dignity maintained throughout the trial. It has been a very difficult time for them.
“Although Walker has been found guilty of murder, we are still trying to identify the driver of a blue BMW which was found burnt out in the area which we believe could be linked to this offence.”