The critical care nurse encounters victims of violence and abuse in the clinical setting. From these patients or from their visitors, evidence can be collected that, when used in legal proceedings, may interrupt the cycle of violence if a perpetrator is identified and found guilty by a court of law. Evidence may be tangible or intangible, and includes what one hears, smells, sees, and touches. This article discusses proper evidence recognition, collection, and preservation. With an understanding of proper forensic techniques, the critical care nurse can be an outstanding patient advocate.