Methadone, codeine and acute haemorrhagic necrotising pancreatitis: which came first?

Acute haemorrhagic necrotising pancreatitis lead to the death at home of a young female who was on a methadone maintenance programme. Toxic levels of codeine with potentially lethal levels of methadone and morphine were found at post-mortem. Whether opiates caused the pancreatitis or were the consequence of self-medication for pain is impossible to differentiate. Forensic toxicology may pose the question but be unable to provide the answer.