A man who stabbed to death his step-father as he lay defenceless on his settee has been jailed for life after being found guilty of murder.

Mark Berry, 49, was knifed seven times in the chest by Darren Gregson, a reclusive loner who had been drinking strong cider.

Yesterday the Recorder of Leeds, Judge Norman Jones QC, sentenced Gregson to life imprisonment and ordered that he serve a minimum of 12 years.

During the trial at Leeds Crown Court the jury heard that the large kitchen knife wielded by Gregson penetrated Mr Berry's heart in the violent attack at the family home in Spring Bank Drive, Norristhorpe, Liversedge.

Yesterday the jury unanimously convicted Gregson, 30, of murder. He claimed he had no recollection of stabbing Mr Berry, an alcoholic, who had provoked him over a number of years.

But after the murder verdict Mr Berry's sister, Pat Philbrick, of Mirfield, said her family welcomed the jury's verdict. "We are very happy with the result. I sat in that court and listened to the evidence objectively and I certainly would have found him guilty."

She said that although her brother was an alcoholic he did not deserve what had happened. "I lost my dad 12 years ago when he committed suicide and now my brother is murdered,"she told the Telegraph & Argus.

Gregson told the jury he was suffering from delusions and depression at the time of the killing. He said he was hearing voices and seeing people who weren't there.

He told how he had suffered years of verbal taunts and abuse from Mr Berry, a former Tesco manager in Cleckheaton, who married his mother Gillian in 1989.

The court heard how Gregson, who trained as a tree surgeon and landscape gardener, had given up his work because he suffered from epilepsy and depression.

Gregson told the jury his stepfather had attacked his mother and he had seen her with bruising.

But prosecutor Andrew Campbell QC said that Mr Berry had no defensive injuries. He had suffered nine chest wounds during what must have been a deliberate and sustained attack. Gregson's mother Gillian and sister Vicky wept in court as the verdict was announced.