A woman could not have lived with the guilt if she had injured her four-year-old adoptive son, a court heard.

John Smith had 54 bruises and four adult bite marks on his body but his adoptive mother denied causing him harm.

Michelle McWilliam, in interviews with police, said her husband Simon did not cause them either.

She said: "I believe Simon would have told me. I did not see Simon hurt John at all.

"I would not want to live with that guilt if I had done something. I believe Simon was the same. As far as I know, he did not do anything."

John died of a brain haemorrhage and the couple, of Gardner Road, Fishersgate, Southwick, deny cruelty and insist the boy self-harmed.

During the interview, read to the jury at Lewes Crown Court, Mrs McWilliam denied pulling out the boy's hair and creating a bald patch.

She said John told her he did it himself to make his hair grow longer but she conceded she had never seen him do it.

Mrs McWilliam could not explain the bite marks, although she had bitten him once during a dinosaur play game, saying: "I did not hurt him, that I can recall."

She was asked about the child's split frenulum, a flap of skin joining the upper lip to the gum. She said she knew nothing about it and had not noticed it.

Mrs McWilliam said she never got angry with John and never smacked him: "I tapped his bottom with a book once when he was going upstairs to bed."

She said she was not especially worried about his self-harming injuries because the couple had told social workers.

She said: "They are supposed to be experienced. They said this was normal, they said things would settle down. Why should we be worried about it?"

Neighbours heard unusually loud banging in the couple's home the day before John died. The adoptive mother said it could have been banging on a cot or toilet but she couldn't explain it.

Mrs McWilliam was shown a photograph of John's head injuries which included a large bruise on his forehead. She said she had not seen the bruise before, saying: "I don't want to comment any more."

A tear at the base of the boy's penis was also unexplained although the boy told her he injured himself.

Mrs McWilliam again insisted she had not hurt him.

The prosecution is expected to conclude when the trial resumes on Tuesday.