Crime scene investigation (CSI) is the process of collecting and analyzing evidence from a location where a crime has occurred. Investigators, often called forensic scientists, work to gather physical evidence such as fingerprints, DNA, and other materials that can help identify suspects and understand the events that took place. The goal of CSI is to reconstruct the crime scene and provide accurate information for law enforcement and legal proceedings. Techniques used in this process include photography, sketching, and the use of specialized tools to preserve evidence, ensuring that it remains intact for further analysis in a crime lab.