Whenever a crime happens, the place it happens in instantly becomes a crime scene. First on the scene will be police, to seal off the immediate area, to avoid disturbance to the scene and evidence. If a body is present at the scene, a physician is brought in to examine the corpse and be fully aware that this is in fact a death. This must be done with as little disruption to the scene as possible.

After notes and photographs are taken, the body is removed to the morgue. The crime scene is cordoned off until the crime scene is examined. Crime Scene Investigators, or CSIs, in the United States, and Scene Of Crime Officers, or SOCOs, in the United Kingdom, examine the scene. This will include documenting every relevant detail, photographing the scene, and collecting any evidence. This is carried out as quickly as possible, as some evidence may deteriorate over time.

Those examining the scene draw up a grid of the crime scene. Any evidence found is noted on the grid, starting with obvious evidence such as weapons, spatters, pools of blood, tire treads, and such.

Next a more meticulous “fingertip” search is carried out, looking for the tinier clues such as bullets, fibres and hairs. If there are insects present at the scene, they may be collected and later examined by a forensic entomologist. All evidence is carefully collected, placed in individual plastic bags or boxes, and labelled with the location, time and date, and signed by the officer who discovered it.