Harry Roberts, the killer of three unarmed police officers in West London, was released from prison after 48 years on Tuesday, BBC reported. The 78-year-old was reportedly jailed for life in 1966.

Roberts, who is reportedly Britain’s longest-serving prisoner, was released from Littlehey Prison in Cambridgeshire. The decision was reportedly criticized by the victims' families after a parole board decided last month that he was eligible to be released. John Tully, chairman of the Metropolitan Police Federation, or MPF, termed Roberts' release as “sickening.” According to reports, Roberts, who narrowly escaped the death penalty, finished his minimum 30-year sentence 18 years ago but was not deemed suitable to be freed until last month.

“Offenders on life sentences are subject to strict controls for as long as their risk requires them. If they fail to comply with these conditions they can be immediately returned to prison,” a spokesperson for the Ministry of Justice said, according to BBC. “Offenders managed through multi-agency public protection arrangements (Mappa) are monitored and supervised by probation, police and other agencies.”

The officers were reportedly shot in the Shepherd's Bush area of West London after they approached a vehicle that was carrying Roberts and two others. Sgt. Christopher Head, 30, and Detective Constable David Wombwell, 25, were shot by Roberts while one of his accomplices, John Duddy, shot 41-year-old constable Geoffrey Fox. The incident triggered a massive manhunt and Roberts was captured three months in hiding, and was reportedly convicted of all three killings.

Last month, the MPF reportedly took the legal step of challenging the parole board's decision to release Roberts. 

“Police officers up and down the country will be absolutely furious and disgusted that Harry Roberts has been released,” Steven White, chairman of the Police Federation of England and Wales, said, according to local reports.

The two other convicts in the case, Duddy and John Witney, were also given life sentences, BBC reported. In 1991, after serving nearly 25 years in prison, Witney was reportedly released on license and was found dead eight years later. Duddy too is reportedly dead.

“Of course I regret it. If anyone had killed my mother I’d never have forgiven them,” Roberts said in an unpublished interview nearly six years ago, according to Mirror Online. “I totally understand why the families could never forgive me and wouldn’t want me released. But I feel I’ve served my time.”