The mother of the man accused of killing New Zealander Emily Longely says she did not realise the teenager was dead when she went to try and wake her up.

Anita Turner, 51, told Britain's Winchester Crown Court that her son Elliot did not murder Emily in his bedroom at their home.

She denies helping to destroy a letter the prosecution alleges was Turner's confession to the crime, or that she knew Emily was dead an hour before an ambulance was called.

Turner, 20, denies the murder of 17-year-old Emily at the house in Bournemouth in May last year but he admits perverting the cause of justice.

Mrs Turner and her jeweller husband of 22 years, Leigh, 54, both deny perverting the cause of justice.

Mrs Turner told the jury Emily had health and emotional problems.

On three occasions she had tried to wake Emily when she was staying in Turner's room but the teenager failed to respond. On one occasion it had taken her 25 minutes to rouse Emily because she had been drinking the night before.

On the morning of May 7, Mrs Turner said her son woke her up and asked if she could wake up Emily.

However, she did not respond, despite repeated efforts.

"I said, 'there is something really wrong - she does not move'.

"He (Turner) said, 'I think she got a terrible, terrible headache last night'.

"I didn't know what to do. I called my husband."

Mrs Turner said she did not call an ambulance because she did not believe Emily was dead.

The prosecution alleges that a violent and jealous Turner strangled the part-time shop assistant.

When arrested he had his passport in his pocket and his bags packed, the court heard.