Three prison guards and their supervisor have been fired from an Ontario prison, almost three months after an inmate's apparent suicide.

Ashley Smith, a 19-year-old from Moncton, N.B., was found unconscious on Oct. 19 in her cell at the Grand Valley Institution for Women in Kitchener, Ont. She died in hospital of what police would only describe as "self-initiated asphyxiation."

The four employees, who had been suspended without pay soon after the incident, were told Wednesday that their jobs were terminated, Corrections Canada told CBC News on Thursday. They were earlier charged with criminal negligence causing death.

Another four guards were suspended without pay for 60 days.

The decision to fire the employees came after an investigation by Corrections Canada, according to Janine Chown, a spokeswoman for the federal agency.

She would not provide details about the investigation.

Union says management to blame

The union representing the prison guards insists they did nothing wrong. On Thursday, some union members picketed the Grand Valley Institution in protest, while other protests were planned around the country.

"They've declared war on 6,000 correctional officers across Canada," said Jason Godin, Ontario regional president for the Union of Canadian Correctional Officers. "We feel that the people really responsible for this tragedy are not being held accountable."

'We're behind these members 150 per cent. They did everything they could to try to preserve the life of this individual.'—Union spokesman Jason Godin

Godin said Smith died because of problems in Canada's prison system, not because of the actions of the employees.

The union, in a statement issued Thursday, accuses Grand Valley Institution and Corrections Canada's women's sector in general of having "disastrous management," where frontline staff were not supported.

"Those senior managers who made the wrong decisions in the case of Ashley Smith are not suffering the consequences of their decisions," the statement alleges.

"Instead, they are disciplining the correctional officers they forced to work in an impossible situation."

Facing possibility of life in prison

The union said the fired prison guards have lost their careers, have lost the means to feed their families and now face the possibility of being sentenced to life in prison, if found they are found guilty of the charges they face.

"We're going to be doing everything we can to defend them," Godin said. "We're behind these members 150 per cent. They did everything they could to try to preserve the life of this individual."

The fired employees — Karen Eves, 52, of Kingston,  Valentino Burnett, 47, of Stoney Creek, Blaine Phibbs, 31, of Caledonia and Travis McDonald, 36, of Cambridge — are scheduled to appear in court on Feb. 5.

Waterloo regional police have never elaborated on the circumstances surrounding Smith's death, except to say that she didn't hang herself.

Smith was serving a six-year sentence for a range of offences, including assault with a weapon and assault a peace officer.