SMIRKING and grinning, Billy Dunlop thought he had got away with murder - and he did for 17 years.

But last night, he was beginning a life sentence for killing North-East mother Julie Hogg after legal history was made in London.

The self-confessed killer thought he could escape justice, but he had reckoned without the remarkable determination of a mother who refused to give up on her murdered daughter.

Yesterday, Ann Ming watched at the Old Bailey as Dunlop received a life sentence, with a minimum tariff of 17 years, for murdering her daughter, Julie Hogg, in November 1989.

She emerged from court to thank The Northern Echo for its part in helping her change the 800-year-old double jeopardy law that had protected her daughter's killer for so long.

Dunlop was tried twice for killing Teesside pizza delivery girl Julie. On both occasions the jury could not decide if he had done it.

After the second trial, he was formally acquitted, giving him the protection of the double jeopardy law - the principle that you cannot be tried twice for the same crime.

Dunlop appeared to be laughing at the law when he later boasted to a prison officer that he had indeed killed the 22-year-old.

The confession came in 1999 after he was jailed for a separate assault and told the prison officer there was nothing anyone could do about his guilt because of the double jeopardy law.

The confession led to him being charged with perjury and jailed for six years.

Following an unprecedented change in the law, he was eventually charged with murder again this year.

Yesterday, justice finally caught up with the 43-year-old, thanks to Mrs Ming, who fought for the change in the law, with the support of The Northern Echo.

Dunlop became the first person to be charged twice with the same offence after the double jeopardy laws were scrapped.

Julie's disappearance was initially treated as a missing person inquiry.

But 80 days later, Mrs Ming found her daughter's decomposing and partially mutilated body behind a bath panel in her Billingham home.

Mrs Ming, 60, and her husband, Charlie, 81, travelled to London from the family's home in Billingham, to see Dunlop jailed.

She sobbed as Andrew Robertson QC, prosecuting, described Julie's injuries.

He said: "The overwhelming inference is that the deceased rejected him and was subjected to a violent sexual assault."

Dunlop had said he strangled Julie after she taunted him about a black eye, but this was not accepted by the prosecution.

Mr Robertson had told the court: "Now the law has changed, in large part due to the long and persistent campaign by Mr and Mrs Ming, who felt they and their daughter were being denied justice."

An impact statement from Mrs Ming was read to the judge, Mr Justice Calvert-Smith.

In it, she said the shock and after-effects of finding the body after police had failed to discover it during a search "verges on the indescribable".

"To this day, I can still smell the putrefied smell which was our daughter," she said.

"As a family, we are damaged beyond repair and will never be the same again as Julie will never return home. The love we feel for Julie means it is we who are serving the life sentence."

Julie, who was separated from her husband, had a son, Kevin, who was three when she was murdered.

He was not in court yesterday, but his statement described how his grandparents had tried to shield him from the truth by telling him his mother had died in the bath.

He only discovered what happened when he was 13 and was taunted by other children at school.

He said: "I have missed out on a mother's love. I have missed out on a childhood.

"I have never been able to understand why the man who killed my mother had not been caught by police and sent to prison.

"I wish I could remember more what my mother was like. All I have are a few photographs."

Timothy Owen, defending, said Dunlop had confessed through remorse and because he wanted to make a clean breast of his crime.

Mr Justice Calvert-Smith said: "It is impossible to comprehend the shock and horror felt by her mother as she pulled away the panel and discovered her remains."

He said there were signs of sexual degradation to the body before it was concealed.

The judge said that he could not take into account violent crimes committed by Dunlop since the murder, but they would be considered by the Parole Board, which would eventually decide when he would be released.

After the case, Mrs Ming paid tribute to the people who had helped her campaign and also to the support of The Northern Echo.

Her voice breaking with emotion, she said: "It's taken 17 years to finally hear a judge give Dunlop 17 years for our daughter.

"I would like to thank everyone who helped with our campaign, Cleveland Police and The Northern Echo, who helped win justice for our daughter."

Martin Goldman, a lawyer for the Crown Prosecution Service, said: "William Dunlop is a dangerous killer whose sentence reflects the premeditated and truly horrendous nature of his crime."

He added: "He has tried to escape responsibility for the murder of Julie Hogg for nearly 20 years and has put her family through great suffering in the process."