Police forces conducting an audit of retained organs have found 492 body parts kept "unnecessarily" and sometimes without the knowledge of families.
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The parts, some of which date back to 1960, were discovered in hospital mortuaries and even police stations themselves.
The audit of police forces in England, Wales and Northern Ireland, was ordered in 2010 after it became apparent that human tissue from murders and suspicious deaths had been retained following post-mortem examinations.
The snapshot survey looked only at major organs and limbs, although some forces have looked separately at smaller tissue samples.
The police fall outside the remit of the Human Tissue Act, which introduced a strict code of practice for all sectors that have any responsibility for human tissue.
This followed the 2001 inquiry into the retention of children's body parts at Alder Hey in Liverpool and Birmingham Children's Hospital, when it was discovered thousands of tissue samples and organs had been kept, sometimes without the permission of the parents.
'Duty of care' to bereaved
A coroner can order the retention of human tissue if it is to establish the identity of a person or a cause of death.
Debbie Simpson, deputy chief constable of Dorset Police, who co-ordinated the audit for the Association of Chief Police Officers, said that the samples had to be kept if they were integral to the investigation.
She also said that if a person was jailed, for instance, their samples should be kept until the prisoner was released or died, in case there was an appeal.
Nevertheless, Ms Simpson said that the police service had a duty of care towards the families of those who died in suspicious circumstances or in homicide cases.
A decision on whether to inform the families has been dealt with on a "case-by-case basis", the report said.
The highest number of organs and limbs retained was by the Northern Ireland police force, which was found to have 71 items dating back to 1960. A total of 13 police forces said they did not hold any body parts.
Ms Simpson said it was clear that this was an area in which the police service needed to work with criminal-justice partners - including coroners, pathologists and defence experts - to ensure they adopted and followed good practice.
In Scotland, the Procurator Fiscal Office is responsible for evidence held in criminal cases, but an audit found that between January and November 2006, organs had been retained on 22 occasions, although some of these for short periods only.
28 July 2011