Scene of the crime investigation is the assembly point of logic, law and science. Processing scene of the crime is a tiresome and long procedure which entails documentation purposely of the situations in the scene and gathering of physical evidences that will probably shed light on what occurred and will point who did the crime. The crime laboratory will does something about the evidences to restructure the crime or recognize the perpetrator or criminal and the lawful matters involved in ensuring that the evidences are permissible in the court.
At any scene of the crime, a crime investigator may gather a piece of dried blood in a windowpane, by not allowing his arm touch the glass if ever there are some unseen fingerprints there, pick up hair from the jacket of the victim with the use of tweezers but not disturbing the clothes enough in shaking off some white powder (which might be cocaine or not) in the crumple of the sleeves and make use of sled hammer in breaking through the wall which looks as if it is the source of an awful smell.
The physical proof itself is just a component of the investigation. The final objective is the strong belief of the person responsible for the crime committed. Therefore, while the crime investigator scratches off dried piece of blood without staining some prints, picks up many hairs by not disturbing some traces of proof and smashing through a partition in the room, he thinks about all needed procedure to preserve all evidences in their present forms.
The scene of the crime investigation starts when the crime investigation unit accepts a call coming from police authorities or detectives on the crime scene. On reaching the crime scene, the investigator makes sure that the place is secure. Then he/she does a primary walk-through in order to get the entire feel of the scene of the crime, see for himself/herself if anybody has moved or touched anything his/her arrival and then he/she makes initial theory out of the visual assessment. Then he/she notes down some potential evidences. At this instance, he/she do not touch anything.