The mother of a ten-year-old boy who was smothered by his father told today of the days when she felt she hated the handicapped boy and "wished it was all over".

In an interview with police after Jacob was killed, Mary Wragg said: "It was just an awful thing for Jacob to experience."

Mrs Wragg, 41, was for the third day giving evidence against her husband Andrew Wragg, 37, who smothered Jacob at the family home in Henty Close, Worthing, last July.

In the police interview, Mrs Wragg said she felt her husband wanted to save Jacob from further suffering as the degenerative condition Hunter syndrome worsened.

Mrs Wragg stressed she had been sympathising with Wragg's feelings but she never thought he would kill their son.

She told Lewes Crown Court today: "I was trying to sympathise with Andy. There were times when Jacob's life was difficult...but that does not excuse his murder."

Wragg, a former SAS soldier, denies murder but admits manslaughter on the grounds of diminished responsibility.

He told police it was a mercy killing when he put a pillow over Jacob's face.

Mrs Wragg, occasionally weeping, went back over her interviews with police after the killing.

She told officers Wragg had been shocked at how Jacob's condition had deteriorated when he returned from Iraq, where he had been working in private security.

She said her son had deteriorated: "Jacob was not there half the time. He was gone. I hate it, too. There are days I hate Jacob and there are days I wish it was all over. It was frustration and pain."

Mrs Wragg said she felt her husband had wanted to "save Jacob from all the trouble that was going to happen".

She told the court earlier that she had nothing to do with the killing. She said yesterday that her ex-husband repeatedly said he wanted to terminate Jacob's life but that she never thought he would carry it out.

Defence counsel Michael Sayers QC suggested she had prior knowledge Jacob would be killed but Mrs Wragg said: "No matter how many times you try and trip me up, I did not kill Jacob and I was in no way complicit with any person."

Andrew Wragg, who denies murder but admits manslaughter on the grounds of diminished responsibility, spoke to Mrs Wragg about killing Jacob just hours before the boy's death at the family home in Henty Close, Worthing, last July.

Later that night he asked Mrs Wragg to take their healthy son George to her mother's just minutes before he smothered Jacob.

Mrs Wragg, 41, said she thought he had completely different plans and had wanted George out of the way so the couple could be left alone to have sex.

She said: "If I felt my son would be killed, having loved and cared for him for ten years, I would not have left him on his own...I can't say it any clearer."

But Mr Sayers said Wragg, a former SAS soldier, had been out drinking and there had been uncertainty in her mind about his intentions.

He asked: "If you thought there was a danger he might mean it why did you leave the house? Why not wait until he arrived home to see what mood he was in?"

Mrs Wragg replied: "I did not believe he (Jacob) was in danger. I did not believe he (Wragg) was capable of murdering our son."

Mrs Wragg, in a statement to police after the killing, said Wragg told her he read it in Jacob's eyes that the boy had "had enough". She said Wragg told her he was not going to let Jacob suffer. At one time, he said: "I'm not doing it for you, I'm not doing it for me, I'm doing it for Jacob."

Their son suffered with the degenerative Hunter Disease and was not expected to live beyond his early teens.

Mrs Wragg accepted that Wragg told her he was going to end Jacob's life and then ring police. She agreed she once said "Jacob was not Jacob" any more.

She said: "It was not the Jacob that Andy knew, the child he used to spend time with, take swimming before it got too embarrassing for him. That was not the Jacob he knew."

Wragg, she said, was of the opinion Jacob's life was not worth living.

She said Wragg told her and others he would never let Jacob suffer. She would defend him, saying that was how Wragg coped. He felt impotent, helpless and unable to do anything about their situation.

All they could do was watch Jacob deteriorate.

Mrs Wragg said social services provided day-to-day help for Jacob but it was a "continuous battle" finding part-time residential respite care.

She never wanted Jacob in full-time care. She wept as she said she would never let Jacob die without her being there and away from his familiar surroundings.

Mrs Wragg told of the hours before Jacob was killed. She was having her nails manicured when Wragg arrived home. He had been drinking and wanted to watch racing on TV.

She said: "He was walking around restless and did not seem to want to hang around."

Wragg left again for his drinking club and said he may be back later that evening.

Wragg telephoned later and spoke to Mrs Wragg about Jacob's condition and felt their son was deteriorating. She said: "I realised Andy had been drinking. He started talking about Jacob's quality of life, how he was going on holiday and when he returned he would take Jacob away, inferring he would end his life.

"He felt he was getting too difficult. I didn't take it seriously...I had heard similar things before."

Wragg, who had worked in private security in Iraq, had discussed Jacob's death with a friend in the club.

Mrs Wragg said: "I said to him 'Don't talk like that - go back to Iraq, get another tour under your belt, get some money and sort yourself out'."

She later sent Wragg a text message suggesting they should have sex that night. She wanted to spend time with him before he went on holiday the following week: "I still loved him and did not want to be fighting."

She took a bath, drank wine and put on makeup to prepare herself for Wragg.

At 9.30pm Wragg phoned telling his wife to take seven-year-old George to her mother's for the night.

She protested about the lateness of the hour but George was awake and she put his dressing gown on him and drove first to a BP garage at Safeway on The Boulevard, Worthing.

She bought crisps, drink for George, squash for Jacob to drink in the morning, and sparkling wine.

She stopped her car at the rear of St Andrew's Church, Tarring, to open George's crisps. Thoughts of what Wragg said he might do to Jacob went through her mind.

She was drinking a mouthful of wine in the car when her mobile phone rang.

Wragg told her: "I have killed Jacob...and I'm going to call the police."

Mrs Wragg told the court: "I did not believe it. I did not know if it was true. I did not want to alarm George...I tried not to say anything. I said 'Just wait there'.

"He hung up and then rang back. He did not say anything. I heard him crying."

Mrs Wragg dropped off George at her mother's home and returned to Henty Close. She found Wragg kneeling and cuddling their dead son.

She said: "He was just holding him and kissing him and holding his hand."

Police arrived and Mrs Wragg tried to stop officers' attempts to revive Jacob: "I said 'Please don't resuscitate him. Please find his notes. Don't do this'. But they kept telling me to back away and I tried to stop them.

"I was getting hysterical and distressed."

Mrs Wragg said she would have called police earlier if she had been suspicious about Wragg's intentions: "We were married 13 years and I had no more reason to believe him this time that he was going to carry out the things he had said."

Mr Sayers pressed Mrs Wragg: "You knew what he was going to do. He told you to leave the house so he could do it."

Mrs Wragg replied: "That is not true."

Mr Sayers: "You have painted a picture of Andrew Wragg which I'm going to suggest is inaccurate.

"He is not perfect, certainly not able to cope, not perhaps a good husband...but you have exaggerated the picture in order to put him in as difficult position as possible."

Mrs Wragg replied: "I'm so sorry but that is not true. I loved him very much despite all of that."

She told police how her ex-husband said after the killing that he didn't care if he served 20 years in prison for Jacob's death, that it was the best thing that could have happened to their son.

The hearing continues.