The Parole Board of Canada granted the 71-year-old an additional six months parole on Nov. 21, stating board members found that by all accounts he is doing well and respecting conditions the board imposed.
"While mindful that the victims of your crime remain deeply affected by your actions," reads recently obtained documents, "with no evidence that your risk is increasing and given the positive work you have done throughout your incarceration and community supervision, the Board finds that your risk to reoffend is not undue..."
Warren was sentenced to life in prison for second degree murder in January 1995 in the killing of nine replacement workers during an acrimonious strike at the Giant Mine.
He was found guilty of rigging a trip wire that detonated a massive dynamite explosion deep underground when it was snagged by a passing ore car holding the victims.
He confessed to the crime 13 months later, retracted his admission at trial, but was convicted and then many years passed before he took full responsibility while in prison in 2003.
At sentencing, the judge called the bombing "nothing less than an act of terrorism," noting many lives were devastated.
Warren said his original motive was to disrupt mining operations and strengthen the union's bargaining position. But he later told an undercover police officer that casualties were justified in a strike that was similar to a war, state the documents.
The board has reimposed special conditions for his release, including reintegration counselling, abstaining from alcohol and abiding by a ban on contacting victims' families.
The two members who made the decision state that Warren has completed all recommended programming and has been deemed "highly accountable and motivated to live a law abiding life."
"Since your incarceration your behaviour has been consistently positive, aside from one infraction in 1999," the board states. "You remained respectful in all relations, both in the institution and the community."
The man was being held at the Mission Minimum Institute, east of Vancouver, when first granted day parole last June. He was ordered to live in a halfway house, although where he may be residing now is unclear.
His case management team reported Warren has been diligently attending supervision meetings and has engaged in extensive volunteer work since leaving prison. They say the main challenges he's faced have involved coping with emotions relating to the murders.
Although Warren was first eligible for day parole in October 2010, he did not apply until 2014. The documents stated he completed five months of day parole without incident.