Rebecca Harvey faced James Watson at the Old Bailey as he was sentenced for strangling six-year-old Rikki Neave and leaving him naked in 1994. Watson, who was 13 at the time, lured the boy into woods near his home and throttled him with his own anorak.
The perverted killer stripped off Rikki’s clothes and arranged his body in a star position for his own sexual gratification, the court heard.
Watson, 41, believed he had got away with murder when police wrongly accused Rikki’s mother Ruth of the killing in Peterborough, Cambridgeshire.
She was cleared by a jury and later pressed detectives to re-open the case.
Yesterday, Ms Neave, 53, described Watson as “pure evil with no conscience.”
The killer was arrested in 2016 after scientists found his DNA on Rikki’s clothes.
He denied murder and fled to Portugal but was extradited back to Britain to face trial.
Jurors at the Old Bailey found Watson guilty in April and he was jailed for life yesterday. Mrs
Justice McGowan ordered him to serve at least 15 years in custody before he can be considered for parole.
The judge said: “Rikki was a child too willing to trust and engage with strangers.
“He never had the chance to be happy and lead a normal and fulfilling life.”
Watson showed no emotion when Rikki’s sister broke down as she addressed the court.
Ms Harvey said: “Although I was the eldest, it wasn’t like that as he would look after me. Losing Rikki was like losing the other half of me.”
Turning to Watson she said: “After all these years of living your life, you finally get your comeuppance, and Rikki finally gets justice.”
Watson, a petty thief with a hatred of police, had a morbid fascination with child murder.
Jurors heard how Watson allegedly sexually assaulted a five-year-old boy 18 months before he murdered Rikki.
Former Assistant Chief Constable Paul Fullwood, who led the investigation, said: “It has taken significant time to get to this point. But we made a promise we would find the person responsible for Rikki’s death and it’s a promise we have kept.”