An “abhorrent” killer rapist who murdered a teenager nearly 50 years ago has been told by a judge he will likely spend the rest of his life behind bars in the oldest double jeopardy case in England and Wales. Dennis McGrory was 28 when he sexually assaulted, stabbed and strangled 15-year-old Jacqui Montgomery during a “horrific, violent and sustained ordeal” at her home in Islington, north London, in 1975. The 75-year-old was cleared of murder the following year on the directions of a judge but was finally convicted decades later after swabs from Ms Montgomery’s body produced a one-in-a-billion DNA match. The victim’s family described the decades McGrory spent out of prison as “soul-destroying”, with her sister Kathy Montgomery saying they “knew he’d done it from day one”. 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. On Friday at Huntingdon Crown Court, Mr Justice Bryan jailed him for life with a minimum term of 25 years and 126 days, and described the killer’s crimes as “abhorrent” and “hideous” – saying the idea a man could inflict that level of violence on a 15-year-old girl “beggars belief”. The retrial, which was scheduled for March last year at the Old Bailey, was halted when the defendant, of Milton Keynes in Buckinghamshire, fell ill. He appeared for his retrial at Huntingdon Crown Court by video-link and was found guilty of rape and murder last month. The jury deliberated for just over an hour to convict McGrory on both charges.