The "chilling" recordings of the last minutes of David Barnshaw's life were also accidentally relayed live to a number of other people.
The sounds of Barnshaw, 34, being assaulted in Stockport, Greater Manchester, and killed were captured by a second victim, locked in the boot of the kidnappers' car, who rang the police on his mobile telephone.
The victim accidentally activated a second phone in his pocket, which automatically dialled up a series of pre-recorded numbers and relayed the sound of the beatings.
Police hope that details obtained from the recording will provide vital clues to the identify of the killers. The murder is believed to be part of a drugs feud between rival gangs.
Barnshaw was a drug dealer and former associate of Chris Little, 32, the leader of a Stockport drug gang who was shot dead in 1994. Barnshaw was snatched from the lavatory of the Moss Rose pub at 9.15pm on 20 September.
A gang of four men had waited for Barnshaw in the pub car park for at least half an hour. The men had tried to hide their identify and had used faked Scouse accents.
Two men who walked out of the pub and were about to get into Barnshaw's car were mistaken as the drug dealer and attacked. They were beaten and held in bushes for about 10 minutes until Barnshaw was noticed still in the pub.
One of the men managed to escape but the other was bound and gagged and put into the boot of a black Ford Orion.
The gang then grabbed Barnshaw and took him to the vehicle. His hands were bound and he was pushed to the floor in the back of the car. The man trapped in the boot managed to free himself and ring the police, who automatically taped the call. They heard gang members asking Barnshaw questions and savagely beating him. He was heard screaming in pain.
He was taken on a drive for about 20 minutes before the car stopped at Welkin Road. The boot was opened and the man inside, who has not been named, managed to escape. The gang then set light to the car with Barnshaw inside. A post-mortem examination found he was still alive as the car was engulfed in flames.
Detective Chief Inspector Kenny Caldwell, of Greater Manchester Police, who is heading the murder hunt, said: "You can hear the victim screaming from the beating and violence. It was chilling. Threats and some significant comments were also made." The police tape is being electronically enhanced in an attempt to obtain more details, such as names, and remove background noises. At least one person who heard the beatings after being contacted on the second mobile telephone has contacted the police with further information.
Police believe the murder is part of an ongoing drugs war.
"There are clear indications that there has been some fall- out between drug gangs or syndicates," said Det Chief Insp Caldwell.
Police are trying to trace two men walking through the underpass at the time, as well as the driver of a silver Ford Escort that was in the Moss Rose car park at about 9pm and the occupants of a dark hatchback seen on Welkin Road half an hour later. None is believed to be connected to the killing, but they may have information as witnesses.Reuse content