A coroner will ask the Crown Prosecution Service (CPS) to review evidence in the case of a man stabbed to death after an alleged burglary.
Tattooist Darryl Bundy, 29, was fatally injured at a house in Selvale Way, Felixstowe, at about 8.40pm on December 16 2011.
Kye Chilton, 24, from Ipswich, and his father John Treasure, 55, who lived at the house, were originally arrested on suspicion of murder.
The CPS decided not to charge either man after reviewing whether the use of force had been reasonable and necessary.
Mr Chilton told a coroner's inquest at Ipswich Magistrates' Court that he had stabbed Mr Bundy twice after he burst into the house wearing a mask and hit his father over the head with a rolling pin.
Mr Bundy's family disputed this version of events, saying he had visited the property with his brother to buy cannabis.
Detective Chief Inspector Neil Luckett, from Suffolk Police, said that what happened that night remained unclear.
He added: "I recognise that, for the family at least, justice has not happened."
Suffolk coroner Peter Dean said that "fear and confusion" may have muddied witness accounts.
Recording a narrative conclusion that Mr Bundy died of stab wounds following an incident at a private residence, he added: "The difficulty in looking at all of the evidence is that there are very few independent witnesses.
"We are left with two different scenarios and we can't be sure which is the right one.
"If this was a robbery that went wrong, this is a situation where the niceties of how much force should be used is very difficult to measure."
He will write to the CPS to ask that it reviews the evidence given at the inquest, saying: "If they come to a different view that is of course a matter for them.
"I would like to give them the opportunity to look again if they wish."
Mr Bundy's family declined to comment as they left the hearing.
Giving evidence via video link, Mr Chilton said he had been at his father's house when a man wearing a balaclava and dressed all in black came in through the back door shouting "give me your stuff".
After attacking his father, Mr Chilton said Mr Bundy chased him and he grabbed a knife.
He added: "He was coming at me. I thought I was going to be hit with a piece of wood.
"I wasn't aiming for anything, I was just trying to stop him hitting me and stop him killing my dad."
Mr Treasure said his recollection of the night was hazy but he could remember being hit over the head. He was later treated at hospital.
After the stabbing, Mr Bundy staggered outside and died in the street where paramedics found him in a pool of blood.
It was later discovered he was wearing a pair of surgical gloves under another pair of gloves and had a knife tucked into his sock.
His brother, Stephen Bundy, who was also at the scene, was originally arrested on suspicion of burglary but the CPS ruled that it was not in the public interest to charge him.
He disputed Mr Chilton's version of events and told the inquest that his brother only went into the house to "score some gear".
He denied the pair had covered their faces. Police never found any masks.
"There was a commotion, they were arguing about the size of the bag of weed or something," Stephen Bundy said.
"I saw Mr Chilton strike him and Darryl turned and ran towards me. "
Mr Luckett said Mr Bundy's motive for visiting the house was not clear.
"The CPS can only go on the evidence that is presented to them and their view was that in this case there was not a realistic prospect of a conviction," he added.
Pathologist Nat Cary said Mr Bundy suffered one stab wound to the chest and one to the back.
He added: "In terms of what constitutes defensive action, it's not for me to say if it's proportionate to the threat."
Father-of-one Mr Bundy was born in Colchester and brought up in Felixstowe.
He had recently returned to the Suffolk town after moving to Merseyside with his partner and child.
His mother, Veda Bundy, said he had been a popular man who lived for football and had become a tattooist because of his artistic talent.
In a statement read to the court, she added: "When I heard he had been stabbed, my world came to a standstill. Everything was a blur."
She described how she had rushed to see him lying in the street, adding: "No mother wants to lose a child and certainly not in these circumstances."