A traveller questioned over a postman's death could not be charged because there was not enough evidence against him, an inquest heard on Thursday.
Former soldier Peter Stone suffered fatal head injuries
Joe "Hopey" Price was named as the man police believe was involved in a pub fight in Cottenham, Cambridgeshire, with father-of-two Peter Stone, 37.
He was found with head injuries outside The Chequers and died the day after.
The coroner, recording an open verdict, said there was not enough evidence to return a verdict of unlawful killing.
At the inquest at Shire Hall in Cambridge coroner David Morris said an unlawful killing verdict would have meant Mr Stone, 37, had been murdered.
"There is nothing more that police can do at the moment in the absence of someone coming forward and giving new evidence," he said.
"I have to record an open verdict which is not a cop-out. Coroners have to be satisfied beyond all reasonable doubt that he was unlawfully killed.
"You all want an unlawful killing verdict but that's not possible.
"There is not enough evidence for me to be sure that unlawful killing is appropriate."
The inquest heard police carried out extensive inquiries both in England, Ireland and Europe and could not do any more.
Mr Price, an English traveller who had relatives staying at the Smithy Fen travellers' site in Cottenham, gave himself up to police after they issued wanted notices on him.
Det Sgt Ian Clark, from the major crimes investigation team, said Mr Price claimed to have been the victim of an unprovoked attack at the pub and that he had been beaten up on his way back to the caravan site and dumped into a muddy ditch.
His clothes were so ruined that he had had to dispose of them, the inquest heard.
Despite extensive police inquiries, there was no evidence to corroborate his version of events or to link him to the murder of Mr Stone outside the pub.
The father of two was found on the patio of The Chequers pub
A post-mortem examination revealed that former soldier Mr Stone's head injury was consistent with an "accelerated" fall to the ground either by pushing or someone falling on top of him.
There was no evidence that a weapon had been used or that he had been kicked in the head.
Afterwards his wife, Cheryl, also 37, said she understood it was the only verdict the coroner could come to.
"There are people who know what happened in the pub that night but they have no conscience and will never come forward," she said.