Forensic investigation is mandated not only in cases of criminal Injury or death, but also where an unexplained death has occurred. The registered nurse involved in providing first aid in such a situation should remember that, while taking steps to maintain patient confidentiality, he or she has a duty to co-operate with any subsequent investigation. This article describes the basic management of hanging and strangulation, poisoning and sexual assault, and provides advice on record-keeping, preservation of evidence and the need for obtaining professional indemnity and support from professional bodies.