Jacqui Montgomery's family spoke to ITV News Anglia outside court.
A pensioner who was found guilty of the vicious rape and murder of a teenager nearly 50 years ago in the oldest double jeopardy case in England and Wales has been jailed for at least 25 years.
Dennis McGrory sexually assaulted, stabbed and strangled 15-year-old Jacqui Montgomery in her home in Islington, north London, in 1975.
He was tried the following year on a circumstantial case and cleared of murder on the directions of a judge.
But he was finally brought to justice after swabs from Ms Montgomery's body led to a one-in-a-billion DNA match decades later.
After a 2003 change in the law on double jeopardy, McGrory's case was referred to the Court of Appeal and sent for a fresh trial at the Old Bailey.
McGrory, of Milton Keynes in Buckinghamshire, had previously been found guilty of rape and murder at Huntingdon Crown Court.
Kathy Montgomery, the victim's sister, said her family were "overjoyed" at his conviction and sentence.
Sentencing him to life with a minimum of 25 years and 126 days, Mr Justice Bryan said due to his age, he would “in all probability” die in prison.
The judge told the killer: “I have no doubt whatsoever that you intended to kill her in your brutal attack on her.
“You put Jacqui through a horrific, violent and sustained ordeal in her own home – a place where she was entitled to feel safe.
“In the decades that followed, you must have thought you had gotten away with your hideous crimes.
“How any man could inflict such sexual violence on a 15-year-old child that had done them no harm beggars belief.
“You have shown not one iota of remorse or compassion for Jacqui or Jacqui’s family.
“You cut short that life and deprived her of that life, and all the things she hoped for in that life.”
During the trial, jurors were told McGrory had been "wild with rage" when he killed Jacqui as he tried to track down his ex-partner Josie Montgomery, who was the victim's aunt.
Prosecutor Sarah Przybylska had said: "No doubt furious with rage and wanting to attack Josie, the defendant took out his anger on the next best thing, Jacqui Montgomery, both raping and murdering her."
During the attack, he ripped out a page of the teenager's diary with her aunt's address on it.
Jacqui's body was found by her father, Robert Montgomery, lying on the floor of their living room in Offord Road in the early hours of 2 June 1975.
She had suffered fatal stab wounds as well as blunt force trauma to the face and been strangled with the flex of an iron.
In a victim impact statement, Jacqui Montgomery's sister Kathy said: "A violent man who had been living within our family [raped and] murdered my sister. He has been able to live his life.
"He has spent nearly 50 years as a free man doing as he pleased.
"I find that unbearable when my sister didn't even reach her 16th birthday. His actions caused trauma to so many people and there were no consequences for him.
"The investigation of the last few years has meant revisiting memories of the murder which has caused pain and stress for me and my family and I am relieved that we finally have justice for Jacqui."
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