Cody Haevischer and Matthew Johnston say they were held in solitary confinement without adequate cause for 14 months after their arrests in April 2009.
The men claim they were kept in cells smeared with feces and blood, denied visits with family, exposed to light 24 hours a day and video recorded constantly even when using the toilet.
"The plaintiff's emotions would fluctuate suddenly between anger, bitterness and fear. The plaintiff began to feel like he was no longer the same person," Johnston's statement of claim says.
"He became despondent and was wholly powerless to change his circumstances."
Haevischer and Johnston were each convicted of conspiracy and six counts of first-degree murder in the deaths of six people in a highrise condo unit in Surrey, B.C., in October 2007.
The Crown's theory was that the Red Scorpions gang plotted to murder a rival drug trafficker but that five others, including a neighbour and a fireplace repairman, were also killed to eliminate witnesses.
Haevischer and Johnston have since appealed the verdicts, and on Wednesday filed separate notices of civil claim seeking damages for violations of their Charter rights.
Haevischer said that after his arrest he was placed in solitary confinement in the Surrey Pretrial Centre, where he was moved between filthy cells, had no access to a television or radio and was denied visits with his daughter for two months.
After he was moved to the Vancouver Island Regional Correction Centre, he was kept in segregation and spent one month in an observation cell with a glass wall that allowed guards and inmates to see him at all times, the claim alleges.
Johnston said in his claim that when he complained about the blood and feces smeared on cell walls at Fraser Regional Correction Centre, he was told to clean it up with toilet paper and tap water.
He suffered panic attacks and memory problems and began singing and talking to himself, the claim said.
Both say they suffer from anxiety and mental health problems as a result.
None of the allegations has been tested in court.
The Justice Ministry said it could not comment as the case is before the courts, but B.C. Corrections has the authority to confine individuals if they are believed to be a danger to themselves or others, are at risk of harm or are a security risk to a facility.
The men claim they were told on various occasions that they were being segregated because they faced harm from other inmates or posed a danger to others. But both men dispute these reasons, saying they had no behavioural problems.
The lawsuits allege that wardens were acting on orders from the RCMP team that had investigated the so-called Surrey Six killings.
Both men were released from solitary confinement in June 2010, after a judge ruled that Jamie Bacon, the alleged Red Scorpion gangster who is still awaiting trial, was treated cruelly and unusually while in segregation.
In that case, a B.C. Supreme Court judge ruled that the warden at Surrey Pretrial Centre acted improperly by placing Bacon in confinement and restricting his mail, visits and phone calls under police influence.
After Haevischer and Johnston were convicted in October 2014, their lawyers applied for a stay of proceedings because of the alleged abuses they suffered. But a judge ruled the matter was best dealt with in civil court.
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