Pre-requirements specification tracing concerns the identification and maintenance of relationships between requirements and the knowledge and information used by analysts to inform the requirements? formulation. Some of the knowledge used is tacit and therefore hard to identify and associate with requirements. This paper presents a tool for retrospectively identifying pre-requirements traces from requirements to their respective source material. We posit that poorly sourced requirements may indicate a requirement based on tacit knowledge. We present a preliminary evaluation of our tools performance using a case study.