Police launched an investigation after concerns were raised in the aftermath of a man's death but found there was no misconduct.
David Jones, 46, died in the communal shower area at a property on Bradford Street in Bolton in July 2021 but his mum said she was told he was injured while he was in custody in Bury.
A coroner was unable to determine the underlying cause of death, recording an open conclusion.
It was ruled he died from a brain injury but it was unclear whether this was caused by an assault or drug toxicity.
In the 10 days leading up to his death he was arrested multiple times.
Mother Sylvia Jones said he told her he had fractured his head as police restrained him inside a police cell at the Bury Custody Suite.
She also said when she called 999 to report him missing she had been told to ring 101 and speak to Lancashire Police instead as he had been staying in Preston.
Ms Jones also said his items belonging to her son had been posted through her door by an officer after his death.
Her concerns were addressed in a police investigation.
Detective Constable Carrie Holder, from the Police Standards of Behaviour, told the inquest some lessons had been learnt but there was no finding of misconduct.
She said in relation to his arrest on July 1 for drug driving and being taken to Bury Custody Suite that he had been restrained after putting up a struggle.
She said: “Mr Jones was struggling with officers.
“Reasonable restraint was being used.”
She said in the footage when he left for court there was no sign of his injuries but he had these when he was arrested again the next day.
She said the call handled who told Ms Jones to ring Lancashire Police had accepted this was a mistake.
The police officer said: “This was unacceptable from the call handler.”
She also said the items of Mr Jones should not have been posted through his mother’s letter box.
She said the officer: “Should have received a return receipt.”
The officer concluded: “None of the officers have a case as a result for conduct or gross misconduct.
“There was learning for some of the officers.”
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