CAFFEINE from the equivalent of "20 espresso coffees" contributed to a Queensland prisoner's death in custody, a coroner has found.
Despite a thorough investigation, authorities have no idea how 51-year-old prisoner John Michael Spence was able to ingest the caffeine unnoticed and found no evidence of the drug in his cell.
Mr Spence was being held at the Capricornia Correctional Centre near Rockhampton when he died suddenly on September 4, 2013.
A specialist pathologist found a reasonably cause of death was cardiovascular disease and seizures while his caffeine levels were extremely high.
Another doctor said she believed the caffeine levels, at about 80mg/kg, could not have come from coffee alone.
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