A wealthy jeweller said paranoia led him to believe a letter he found could have been a confession that his son had murdered his Hampshire student girlfriend in their house.

Leigh Turner, 54, told a jury that he did not read the letter from his son Elliot to his mother Anita and he had ripped it up.

He said that all he saw was ''Dear Mom'' in his son's handwriting and he had ''paranoid thoughts of what had happened'' so he destroyed it.

He and his wife Anita, 51, both deny perverting the course of justice.

Elliot Turner, 20, denies the murder of aspiring model Emily Longley, 17, in his bedroom at the family home in Bournemouth.

The prosecution at Winchester Crown Court allege that Turner ''went absolutely nuts'' and strangled the Brockenhurst College in a jealous rage on May 7 last year after he feared she was seeing other men.

He had threatened to kill her and had assaulted her when they argued during the short volatile relationship.

He said she attacked him and he grabbed her by the throat for five or six seconds to defend himself and had gone to bed and woke up to find her dead.

Today 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 Turner failing to call an ambulance.

Leigh Turner told the jury that he had returned home after a call from his wife that Emily ''might be dead''.

''She looked like she was asleep for that split second,'' he explained. ''I knelt down beside her touched her cheek, touched her head and touched the side of her neck. She was cold - ice cold, like a crystal cold. The girl had passed away.

''I said 'sorry butterfly' or something like that, I'm crying. Then in a split second Anita was on the phone and I said, 'call an ambulance'.''

He said that his son had packed a suitcase and he had said to him: ''What are you going for. There is nothing to run from.''

Leigh Turner told the court he had found the letter in some papers at the house when the family had been allowed to return four days after Emily's death.

He said it was in a plain envelope with no writing on and he had taken it into the garden and he destroyed it.

''I just thought the worse.. I didn't know what it was. It might have said Elliot might have had some involvement, or something written down that might have happened that night.

''I cannot think what I thought - it was an entity, a void. I felt numb.''

He later said he had learnt a little of what was in the note when he overheard his wife and son talking about a mallet, an argument and being hit.

He said there was no excuse for destroying the letter but he denied he realised he was perverting the course of justice when he did it.

He also denied taking a jacket from the house when it was a crime scene.

He said the covert tapes when police bugged the house and he was heard to say Elliot had strangled Emily was the ''worst case scenario of what might have happened''.

Earlier the jury heard the prosecution allege Elliot Turner went ''went absolutely nuts'' in a culmination of a month of anger and upset over his suspicions Emily was ''twisting his heart''.

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

He told officers at the scene: ''I never meant to harm her, I just defended myself.'' He then made no comment in police interviews.

Computers seized from the home had Google searches for 'death by strangulation' and 'how to get out of being charged for murder'.

Police bugged the £350,000 family home and recorded Turner's parents ''fabricating evidence'' and being worried about lying to the police.

Anita Turner took away a coat from the scene of the death, it is also alleged.

Emily had been born in Britain but her family had emigrated to Auckland, New Zealand when she was nine.

She had returned to live with her grandparents in Bournemouth, Dorset, to study when she died.

The jury was also told that Turner had received a harassment warning letter from the police in January 2008 when he was 16 telling him not to contact an ex-girlfriend Proceeding.