Environmental crimes are escalating at an alarming rate worldwide, posing serious threats to ecosystems, human health, and sustainable development. The investigation and prosecution of such crimes present complex challenges, often resulting in delayed or denied justice and ineffective environmental redress. This chapter highlights the critical role of Environmental Crime Scene Investigation (E-CSI) as the foundational step in addressing environmental offenses. Unlike conventional crimes, environmental violations demand a broader, more dynamic investigative approach due to delayed reporting, degradation of evidence, and the intricate movement of contaminants. It is proposed that the traditional concept of a 'crime scene' be expanded to a 'crime scenario' to reflect the extended temporal and spatial dimensions typical of environmental harm. Effective investigation necessitates a multidisciplinary approach involving advanced environmental forensic tools, source apportionment techniques through mathematical modeling, and international collaboration. The chapter further underscores how a well-executed Environmental Crime Scene Investigation can facilitate accurate crime scenario reconstruction, enabling the establishment of a coherent timeline of events, the tracing of pollutant propagation, and the identification of responsible parties. Thus, an effective E-CSI serves as the cornerstone of a robust environmental redressal mechanism.