The main reason is that the scene needs to be preserved in order to collect evidence so that the offender or the person who caused the incident can be found. Evidence is gathered in a number of ways:
- Photographs
- Videos
- Forensics
- Witness Statements
If evidence is lost this would cause problems for the police, it could lead to the person to blame not being prosecuted or held to account for damages. To stop this it is important that none of the emergency services personal do anything to contaminate the scene such as moving things around as this would the result in their DNA being on the crime scene, this would then make the jobs of specialist units such as SOCO more difficult.
Other units may be called in to the incident depending on the circumstances, for example if there was a fire fire investigation teams would be called in in order to investigate whether the fire was started on purpose.
When preserving the incident there are also other things that need to be taken into consideration:
- If there any outstanding offenders the route they took to escape.
- Property left at the scene.
- Locations where there are possibilities of finger prints.
- Broken glass.
- Fibres from clothes.
- Cordoning the area in order to keep people out who could contaminate or destroy evidence.
- Any evidence found is put in special bags which are labeled and they protect the evidence from damage and contamination.
- Gaurd the crime scene
- Controlling sightseers
- Protecting the public
- Prevention of unthoaraized intereference with the investigation
- Facillitation of operations by emergency services and related agencies
