A police investigation is a systematic search for evidence of criminal activity. It involves the collection and preservation of evidence and the examination of it by crime laboratory experts. It is an important process for the criminal justice system because it identifies and apprehends suspects. It is also the basis of a prosecutable case in court.
Criminal investigators use a variety of methods to gather evidence such as surveillance, forensic analysis, checking databases, and public tips. They may interview and interrogate suspects and witnesses. They may take photos and measurements of the crime scene, or other physical evidence. They might ask for the help of medical professionals who could examine a victim’s injuries.
When a crime occurs, police officers and detectives immediately begin to investigate. They will examine the scene and note any physical evidence such as weapon marks, blood stains, or the position of the perpetrator. They will also write down their own observations and document them. They will interview any known witnesses who were present at the scene of the crime.
Police detectives are skilled at interrogating people in order to get them to admit to a crime. But they must follow all reasonable lines of inquiry and never violate a suspect’s Miranda rights.
If they have a strong enough case they will arrest the alleged offender. The arrested person must be read their rights before the police can carry out an identification procedure such as a video parade electronic recording (VIPER). Police officers and detectives must have probable cause or a legitimate reason to believe that a criminal offence occurred before they can obtain search warrants, seize property, or make an arrest.