Secret recordings made by police in the house of three murder suspects were played to a jury.
Detectives placed bugs in a house in Neptune Close, Crawley, a week after alcoholic Charmaine Dempsey was found battered to death.
Defendants Alex Gallacher, 33, and Stephen Johnstone, 26, who deny murder, shared the house with Tracey Gazzard, 29.
Gazzard, who was Gallacher's girlfriend at the time, admitted a charge of manslaughter at an earlier hearing on the grounds she assaulted Ms Dempsey but did not mean to kill her.
Ms Dempsey's body was discovered in her flat in Ivory Walk, Bewbush, Crawley, by her daughter on December 29, a month after she is believed to have been killed.
Jurors at Lewes Crown Court were yesterday given transcripts of the recordings and heard more than one and a half hours of the tapes.
Detective Sergeant Kevin Burgess, of the Force crime and drugs unit, said the probe in Neptune Close relayed the inhabitants' voices to police officers nearby and were recorded.
Christine Laing, prosecuting, said the recordings were sent to police in Scotland to help decipher Johnstone's and Gallacher's strong Scottish accents.
In the recordings, which jurors were told last week were "highly incriminating", the three friends are heard arguing.
At 3.45am on January 7, after Ms Gazzard had been questioned by police, one of the men is heard saying: "Us three are alibis to each other."
The trial continues.
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