Covert recordings are central to the case against the British man accused of murdering 17-year-old New Zealand student Emily Longley.
Elliot Turner, 20, pleaded not guilty to murdering Ms Longley when he appeared at Winchester Crown Court on Friday.
He also denied a charge of attempting to pervert the course of justice.
Details of the police case against Turner emerged as defence counsels demanded access to the tapes, the Sydney Morning Herald reported.
Turner's mother Anita is also charged with perverting the course of justice by delaying calling emergency services after Longley was found dead at their Bournemouth home. She and husband Leigh Turner are also accused of destroying "vital" evidence.