If law enforcement asks you to come to the police station for questioning, there is a high chance that you are a suspect or target of a criminal investigation. Regardless of whether you have been contacted by law enforcement as part of an inquiry into an alleged crime or not, understanding what happens during police investigations can be beneficial.
Ideally, when officers respond to reports of a crime they are able to catch the perpetrator on the spot and immediately arrest them. However, that is not always possible, and the task of building a case that will stand up in court falls to the police investigator.
For crimes of a more serious nature, detectives will be assigned to lead the investigation. They will go to the crime scene and look for physical evidence including photographs, measurements, blood samples, footprints, fibers and fingerprints, which can then be sent away for further analysis. They will also interview witnesses.
Police investigators may also review information from multiple sources including surveillance footage, public records and databases. These can then be analyzed to identify patterns and potential suspects. Detectives will also visit victims, witnesses and family members to seek out information. Interviews are conducted in a highly structured manner and are designed to extract as much information as possible.
They will also use surveillance techniques to monitor the movements of a suspected individual or group. As with physical evidence, all of this information must be carefully documented to ensure that it is not tampered with.