The victims had been lying in two rooms of a ground-floor flat in the centre of Slough, Berkshire, for about four days before relatives reported them missing to the police, who broke into the property.
The victims are believed to be a 30-year-old woman, who rented the council flat, her boyfriend, who also lived in the flat and another man, both aged in their 30s. They all had severe head wounds.
The woman was reported by neighbours to have had an open sexual relationship with both men. A friend said all three regularly drank in the town's pubs and that they were not drug users. The bodies were found on Thursday night but details were not released until yesterday.
Detective Superintendent Trevor Davies, heading the inquiry, said: "For the police officers who went inside the house it was a harrowing experience. They found the three bodies in two locations."
He added: "I would like to reassure people in the Slough area that this appears to be a one-off offence. There can be no more serious offence than the killing of a human being but this is not part of a pattern." A friend of the victims, Paul Waby, said the woman and one of the men lived in the flat, although the female victim was also seeing the other male victim.
The man who lived in the flat was a self-employed painter and decorator and the woman had started a job working with the elderly several weeks ago after being unemployed.
The second man, who lived around the corner, worked at Slough railway station.
Mr Waby said the woman met her live-in lover about four years ago but had continued "on and off" to see the other male victim, whom she had known for about seven years.
Both men were aware of the situation, were untroubled by it and remained good friends. A team of 30 officers has been set up to work on the murder hunt. At this stage the police are only looking for one man.
A Home Office pathologist was examining the bodies last night.
Beckie Cherrell, a neighbour who knew one of the victims, said: "He had a small flat in our house but was rarely there and we regularly saw him going into No 2A (where the bodies were found).
"He was a nice bloke, they were both harmless people and whenever I saw him he would always acknowledge me and say hello.
"I just can't believe who could have done this; it makes me feel sick in the stomach and I feel quite frightened, as I only live around the corner."Reuse content