Depositions obtained as part of its operation would ideally be noted on paper, and if possible recorded for the purposes of propaganda.
The ISU carried out debriefing of IRA volunteers following their detention by security forces operating in Northern Ireland.
These interviews would take place to discover if a volunteer had betrayed information or secrets of the organisation.
They would also take place in the event of an operation, weapons cache, or unit being exposed to danger or uncovered.
The membership of the IRA and wider republican community were expected to comply with requests for information made by the ISU, this information then being used to build or refute accusations made against an IRA volunteer.