crime scene investigation is an act or process of collecting physical evidence from the scene of the crime and documenting the same for the purpose of identifying person/s involved in the crime as well as examining the same in order to determine and or analyze how the crime was committed.
CSI is the gathering of potential evidence at a crime scene. A crime doesn't have to be murder contrary to what all the tv shows broadcast. It could be rape or burglary or a physical attack or murder (homicide). Depending on the crime commited, different forensic specialists attend the crime scene. In the case of a murder where a body has been found, a forensic entomologist will investigate the insects on the body. At a burglary, fingerprinting expects will analyse any finger prints lifted from the scene. In the case of rape, any blood and semen from the attacker will be searched for.