A police force will be sentenced for health and safety breaches in relation to a belt used around the face of a man before he collapsed in custody.
Thomas Orchard, 32, died in hospital seven days after being arrested and taken to Heavitree Road police station in Exeter, Devon, in October 2012.
During his detention, Mr Orchard, who had paranoid schizophrenia, was restrained and an emergency response belt (ERB) was placed across his face to prevent spitting or biting for five minutes and two seconds.
The restraints were removed and the church caretaker was left in a locked cell, where he lay apparently motionless for twelve minutes before custody staff re-entered and started CPR.
A post-mortem examination found he died from a severe hypoxic-ischemic brain injury.
In a landmark conviction in 2018, the office of the chief constable of Devon and Cornwall Police admitted breaches under the Health and Safety at Work Act.
The charge alleged that the force failed to ensure non-employees, including Mr Orchard, were not exposed to risks in connection with the US-made ERB.
Last month, a three-day trial of issue was held at Bristol Crown Court for Judge Julian Lambert to resolve a series of disputed matters, including whether the use of the belt was a contributory factor in Mr Orchard's death.
Judge Lambert concluded that he could "not be sure on the issue of causation" as the evidence was "not clear" to him.
Speaking after the ruling, Mr Orchard's mother Alison Orchard said: "As a family, we are nothing but dismayed by the judge's decision. It is really hard to believe after all we have witnessed."
Helen Stone, of Hickman and Rose, the family's solicitor, said the previous guilty plea was the first time any force had admitted health and safety breaches in relation to a death in custody.
She described it as "a positive step forward for justice and the public's ability to hold the police to account for their actions".
The ERB was first approved for use by the force as a limb restraint in a custody setting in 2002 and later used as a spit or bite guard.
Pathologists told the court it was not possible to conclude whether the ERB contributed to Mr Orchard's death.
In a written statement, Shaun Sawyer, the chief constable of Devon and Cornwall Police, said: "The judge decided that he was not satisfied the use of the ERB on Thomas Orchard caused or contributed to his death.
"I respect this decision, indeed it has always been the position of Devon and Cornwall Police.
"My primary thought is for the family of Thomas Orchard. The last six-and-a-half years is something I and no family would want to go through."
The force will be sentenced at 10.30am on Friday.
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