An off-duty policeman attacked on a night out died from a head injury as a result of a single punch.
Three men continue to be questioned on suspicion of the murder of Pc Gareth Francis, 28, in Stockport, Greater Manchester, as a post-mortem examination confirmed the cause of death.
Police and emergency services were called at 1.20am on Sunday to a report of an assault in Castle Street, Edgeley, where Pc Francis was found with a serious head injury.
He had been walking home after being dropped off by taxi from a night out in Manchester with friends when he was attacked. Paramedics treated him at the scene and he was taken by ambulance to Stepping Hill Hospital, where he died shortly afterwards.
Tributes were paid by family and colleagues of Pc Francis, who joined Greater Manchester Police (GMP) in 2007 and served in South Manchester and Wythenshawe before a move to West Didsbury police station last summer.
Pc Francis's immediate supervisor for the last four years, Sergeant Alex Cairns, spoke of him as "a consummate professional police officer".
Sgt Cairns said: "Gareth's colleagues on 'A' relief are absolutely devastated by his death. It has hit them extremely hard and they are being offered all the support that we can right now.
"Most of his career, Gareth worked on a close-knit relief of between 10 and 14 officers, so you can imagine that in teams of that size the news has come as a personal blow to them.
"Gareth was the kind of officer who would quietly get on with his job with the minimum of supervision. In fact, he was pretty much a 'go to' kind of guy. If you needed something doing quietly and efficiently, then he was your man. He would volunteer to stay late without any complaint and approached everything in work with an outstandingly positive attitude.
"All of his colleagues, without exception, felt a sense of relief when they knew Gareth would be attending a difficult or potentially dangerous incident with them. That was the esteem in which his fellow officers held him. He was always the consummate professional police officer."