Body parts were retained by the police in Northern Ireland in cases of suspicious deaths and murders without family members being informed.
The details have emerged following an audit ordered two years ago of all human tissue being held by UK police forces.
In a statement tonight, the PSNI said the audit had enabled officers to "identify and consider the most appropriate way of sensitively dealing with human tissue no longer required to be held for criminal investigations".
Family liaison officers are now visiting the families affected to "inform them and to discuss with them what their options" are.
It is understood the type of human tissue retained includes significant body parts.
Sinn Féin has said it is shocked by the revelations.
In a statement Sinn Féin MLA Gerry Kelly said: “This is a shocking revelation. Our thoughts are with the families of those involved. It is my understanding that the process of informing the affected families has now begun.
“Like previously with a number of hospitals, the retention of body parts and human tissue without the knowledge of families is completely unacceptable.
“It is now important that proper support mechanisms are put in place for the families involved and a proper public explanation for this practice is put forward and assurances given that it will not happen again."
