The mother of Daniel de Costa, who is standing trial for the murder of Devizes man Matthew Baggott, has told a jury at Winchester Crown Court of her problems with him when he was a toddler.

Victoria Bull, who is a Wiltshire probation officer, said De Costa's father, Richard Whittingham, with whom she was married for three and a half years, was a Jekyll-and-Hyde character.

Mrs Bull said: "He was a very strange man. He used to sniff the back of his hands and didn't like the smell of some foods. If I wanted to eat an apple I had to go outside to do it."

She said she first noticed problems with De Costa when he was two years old. She said: "He wasn't like other children. If you told them a radiator was hot, they might touch it once just to check but he would keep on touching it although he knew the consequences."

She said matters came to a head when she took him to her GP surgery on an unrelated matter. She told the court: "In the waiting room he was climbing on chairs, trying to get out of the window, tearing books, annoying the other patients. By the time I got into the surgery I was hysterical.

"I said, if you don't do something I will batter him."

De Costa was sent to a psychiatric hospital in Brighton for assessment but managed to get out of the ward. He was found walking down a street outside.

When he went to school he was aggressive to other children in the playground, though he also was bullied.

When he was seven he dismantled the wardrobe in his room and threatened his mother with the iron hanging rail.

She said: "It was scary. It was like a switch being turned."

When he was 13 De Costa started taking illicit drugs. He asked his mother for money to buy them and when she refused, he began slashing the sofa with a knife.

She said: "He said to me, I'll slash your throat if you don't give me any money."

Mrs Bull asked for De Costa to be tested for drug allergies. She said: "At the clinic I saw him change before my eyes. When they gave him eggs he became depressed and with chocolate he became completely off his head with hyperactivity."

After De Costa was diagnosed with ADHD at the age of 17, however, he was put on a course of Ritalin and Mrs Bull said it was like a miracle.

She said: "Within half an hour he was a different boy."