On the scene - Assessing
At first glance a crime scene may not show anything obvious, but it can contain lots of evidence which can connect someone with a crime.
Police follow strict procedures to prevent evidence being disturbed, contaminated or lost.
The first step is determining the size and boundaries of the scene.
In cases of serious crime, once the extent of the crime scene has been identified - this could be a single room or even an entire street - the area is cordoned off.
The number of people entering the crime scene is kept to a minimum and a record is kept of anyone entering and leaving a crime scene.
Officers also decide whether the site is where the crime actually happened - a primary crime scene - or somewhere the suspect went after the crime was committed - a secondary crime scene .