Police forces have stored almost 500 major body parts, including organs, unnecessarily without telling the families of victims, an official investigation has found.

The Association of Chief Police Officers (Acpo) says the human tissue samples were from murder investigations or cases involving other suspicious deaths that date back as far as the 1960s.

An Acpo audit found that the 492 body parts retained by police forces in England and Wales included brains, hearts and limbs. Officers are now in the process of informing relatives and families of the victims.

Police say there is a legal requirement for them to retain human body tissue samples after a postmortem in murder cases and those where a coroner believes there were suspicious circumstances.

The body parts can be stored "until the convicted prisoner has served his sentence" but it is thought that the samples uncovered by the Acpo audit relate to cases no longer subject to investigation.

The audit did not include samples from current criminal investigations or cases that were still subject to appeal.

Deputy Chief Constable Debbie Simpson, who led the audit, said there was "no nationally agreed policy to deal with such items at the conclusion of the investigation".

Some relatives may not have been made aware that detectives had kept the remains but officers are now in the process of "sensitively" dealing with the human tissue, she added.

When asked whether families were aware that tissue had been retained, Simpson said: "It may well be a case-by-case basis".

"The added trauma and upset which may have been caused to the families is difficult and we apologise for having to open up those issues for them," she added.

Simpson said: "The police service has a duty of care towards the families of those who die in suspicious circumstances or in homicide cases, to ensure such cases are fully investigated while loved ones are treated with dignity and compassion.

"While policing falls outside of the Human Tissue Act, and in each individual case there will be particular reasons why a tissue sample may be taken and then retained as part of an investigation, it is clear that this is an area where the police service needs to work with criminal justice partners including coroners, pathologists and defence experts to ensure that we adopt and follow good practice.

"Protecting the interests of families affected has been central to this audit process. I will continue to work with our partners on behalf of the police service to ensure that we address the recommendations within this report."

The medical secretary of the Coroners' Society of England and Wales, Dr Roy Palmer, said: "The findings of this report illustrate the problems that arise when the purposes and the appropriate authority for retaining human material at forensic autopsy are less than clear. Families affected by the findings of this report are likely to have faced renewed upset in learning that material may have been retained without their knowledge but this review is an important step in assessing and understanding the current picture nationally and provides police services, pathologists and coroners with an opportunity to learn how to improve our processes.

"Coroners have played an active part in this audit and have worked closely with other agencies to understand what material has been retained and whether it is still needed. The Coroners' Society welcomes the Acpo audit as it reinforces the duty on investigation authorities to advise the coroner at the time of human material retention."

© Guardian News and Media 2012

[Female criminologist via Peter Kim / Shutterstock]