A BOY who stabbed his foster carer to death had confronted his mother over the identity of his real father just days before the killing, an inquiry has heard.

The boy had been left angry after he saw his birth certificate which listed a man he knew as his grandmother's boyfriend as his father.

The teenager - who cannot be named for legal reasons - had been asking carers and social workers about his biological father for a year and spoke to his mother about it during a meeting just four days before he stabbed Dawn McKenzie to death.

Yesterday social worker, Steven Lorimer, said the boy's mother told him his real father was a "short, fat, man, who was dead", and that his stepfather was on remand in prison accused of shooting someone.

Mr Lorimer told a fatal accident inquiry into Mrs McKenzie's death the revelations could have had a profound effect on the boy and admitted that he had not handled the meeting well.

He said: "During the meeting, the boy and his mother had started to speak about the birth certificate and his biological father. He asked his mum to clarify why the person on his birth certificate wasn't his biological father.

"I can remember before the meeting that he was upset and angry that a different name was on the birth certificate.

"The explanation was simply that the man he knew as his gran's boyfriend was his mother's boyfriend when he was born."

Mr Lorimer, who works for Glasgow City Council, said the boy then began to ask about the identity of his own father.

"His mum said he was a 'wee fat man' and he was dead," Mr Lorimer said.

"The boy was passive and his expression didn't change. It was negative information, the experience rated very poorly compared to others I have been involved in.

"The comment about his birth father could have had a profound effect on him. I was unprepared for that."

Mr Lorimer, who had been the boy's designated social worker since June 2009, told the inquiry he could not remember if he had passed on the information to Mrs McKenzie following the meeting.

He added: "I would accept that there should have been more preparation by myself and better planning in terms of that kind of information being shared.

"It could have been handled differently."

The probe also heard a diary entry by Mrs McKenzie said the boy's laptop and mobile phone had been confiscated after the discovery of Facebook contact between him and his mother.

She wrote: "We had an incident with regards to Facebook on June 15. He has been using Facebook to contact his mum. I removed both his laptop and mobile phone.

"I called his school and his use of computers will be supervised at all times in class.

"He accepted they were being taken off him to stop contact with his mum. There was no conflict."

The boy - who was 13 at the time - was placed with Mrs McKenzie, 34, and her husband Bryan in Hamilton, Lanarkshire, in November 2010.

She was killed in June 2011 at her home.

The teenager was jailed for seven years in 2012 after being found guilty of culpable homicide on the grounds of diminished responsibility.

The inquiry in Motherwell continues.