Elliot Turner, 20, stands accused of strangling the 17-year-old New Zealander at his home in Bournemouth.

Turner has now pleaded guilty to the charge of perverting the course of justice, admitting that he tried to get his mother to change her story to police. But he denies murder.

His father, Leigh Turner, took the stand yesterday and claimed that he heard nothing on the night that Longley died. He described finding her on his son’s bed, “cold as crystal” to the touch.

When accused of destroying a letter written by his son that allegedly confessed the crime, Leigh insisted that the only words he saw were “Dear Mum”, and that he tore it up and dumped it on his way to work for fear that it might implicate his son in Longley’s death.

He was recorded by a police bug telling his wife: “we’ve perverted the course of justice, that was a confession”.

But he insisted in court that those words were what he worried about being in the letter “in my head … I never heard Elliot say that”.

Leigh did, however, admit that his son was “pulling the strings” and “leading the conversation” about what to tell the police about Longley’s death.