The mother of a British man accused of murdering New Zealander Emily Longley is alleged to have put on an act when she called emergency services to report the death.
Elliot Turner is accused of murdering the aspiring 17-year-old model in his bedroom at the family home in Bournemouth, Dorset.
The prosecution at Winchester Crown Court allege that the accused "went absolutely nuts" and strangled Ms Longley in a jealous rage on 7 May last year after he feared she was seeing other men.
Mr Turner, 20, denies the charge.
Anita Turner gave evidence on Tuesday and was asked why it took 40 minutes to call the ambulance.
The BBC's Ben Ellery, told Radio New Zealand's Morning Report programme Mrs Turner said she called her husband first because she did not want to believe that Emily Longley was dead.
"She said she was just shaking, shaking, shaking her but she wouldn't wake up, while her son was pacing around with his head in his hands.
"However, the prosecution said Elliot had told her exactly what happened, alleging that he had murdered her and she was just going through the motions."
Mrs Turner told the court she promised Emily Longley's grandparents that she would look after the girl.
Ben Ellery reports the 51-year-old became emotional when she said Ms Longley's name and told the court she had been especially close to her and they often went shopping together and had lunch.
Anita Turner and husband Leigh have denied all knowledge of helping to cover up the alleged murder.
On Monday, Elliot Turner pleaded guilty to the charge of perverting the course of justice by persuading his mother to change her story after the count was amended to take away reference to him failing to call an ambulance.
The jury is expected to begin deliberations at the end of this week.