The chief of an NHS trust found to be keeping organs and tissue from police investigations without the knowledge of families has issued an apology.
Northumbria Police has said 26 families are involved in the inquiry launched after it was found the samples and body parts had been kept longer than necessary.
The force and South Tyneside NHS Foundation Trust have said they are working together over the holding of some human tissue samples at South Tyneside District Hospital.
Some of the material - taken as part of criminal and inquest investigations - dates back 20 years.
The samples, which belong to people from across the North East, were found at the hospital, in Harton Lane, South Shields, during an audit two years ago.
An investigation has been launched by the trust to establish why the samples were kept at the hospital for longer than would seem appropriate.
Ken Bremner, chief executive of the trust, said: “I want to express my sincere apologies to all the families involved for the distress and anxiety that this will, undoubtedly, have caused.
“We are currently in the process of reviewing the circumstances around the storage of these samples.
"A review of this nature, covering a time period that goes back over a number of years, will, unfortunately, take some time to conclude, however, I would like to assure the relatives that we will do all we can to complete our enquiries as soon as possible.
“Throughout this process, we will be working closely with Northumbria Police, Cleveland Police, the relevant Coroner’s Office and the Human Tissue Authority and we will support all efforts to respond to concerns arising from these difficult circumstances.”
Temporary Assistant Chief Constable Vanessa Jardine said: "First of all I would like to express my condolences to the families who have been affected.
"This is understandably an incredibly emotive issue and we recognise it has caused a huge amount of upset and angst to those involved.
"Unfortunately what has happened is not unique to the North East and there have been previous incidents across the country following the uncovering of historic practices that led to human tissues being held for longer than necessary.
"It is with regret that the samples were not identified sooner and this is a matter that ourselves and the hospital have taken incredibly seriously.
"We fully recognise the importance of carefully managing the retention and storage of human tissue samples collected for investigative purposes to ensure they are obtained, and retained and disposed of, in line with the Human Tissue Act.
"In 2006 a new law was introduced as result of such errors and, while police are exempt, we fully support this legislation and have instructions in place to prevent this from happening again."