Once a crime is alleged, law enforcement officers will begin to investigate. The complaining witness or aggrieved victim will make a statement and written reports will be made of these statements. If the only witness involves law enforcement, the officers will make written reports documenting what they observed.
If the investigating officer determines that there are other witnesses to the crime, she may take statements from these people.
Evidence, if any, will be gathered at this time by collecting physical evidence located at the crime scene, taking photographs and video images of the scene and evidence, and retrieving relevant evidence from other locations.
Crime scene analysts may be asked to test various pieces of evidence or conduct examinations that may reveal further evidence (e.g., fingerprint analysis, chemical analysis of various substances).