A police investigation is the process of gathering evidence about an offence. This may involve police interviewing you or other witnesses, taking photographs and carrying out tests on items like blood, saliva or fingerprints. Police investigate to establish whether an offence has been committed, and if so, who is responsible.
The investigative process can take a long time, but you’ll be kept up to date at key points. You can agree with the investigating officer how often you’d like to be updated. The police will contact you if they need you to tour the scene or attend an identity parade to identify the offender. Police also gather forensic evidence from the crime scene, such as fingerprints, hair, saliva or blood. It is collected with care, in special bags to preserve it and limit contamination. It’s then sent to labs for analysis, and each piece of evidence is recorded and documented by police. This is known as the chain of custody and helps to ensure it hasn’t been tampered with.
Detectives will pursue all reasonable lines of inquiry to gather evidence that points either towards or away from a suspect. They can use this information to decide what action to take, including arresting and removing the suspect from public view, community resolution or prosecution. They must follow the law regarding searches and seizure of private property, which involves obtaining a warrant or probable cause from a judge.
Detectives are also trained interrogators, and know how to gain a suspect’s trust and get them to confess. This can be a challenging process, and they must not violate a person’s constitutional rights.