Criminal investigation is a field of study and practice that involves the systematic examination and analysis of evidence and information to uncover the truth about criminal activities. Investigative techniques may include interviewing witnesses, collecting physical evidence, conducting surveillance, and using forensic science methods. The goal of criminal investigation is to gather enough evidence to determine whether a crime has been committed, identify the perpetrator, and ultimately bring them to justice. This field is essential in ensuring the integrity of the justice system and protecting society from criminal activities.