. . . The Forensic Crime Scene Technician or the Investigating Detective.
The 'lead' investigating officer/detective is in charge regardless of who is "working" the scene.
Act fairly and follow established rules.
analysis
an investigator is a person so you would yous it as a noun ex: The investigator walked quietly into the church. an investigator can be seen as ether a detective, (because they are investigating the crime) or as someone hoping to broaden their religious beliefs (so they are investigating a church)
I met an officer one time. He did not really go to a crime investigating school or education at all, yet he was a former detective and a SWAT member. Working at a local police station can help. After a few years you will get into the detective position if you do well in patrol.
case
Happens all the time. A detective might consult with a computer specialist, a firearms expert, a locksmith, a physician, etc. The are all specialists in their field.
"Homicide" refers to a crime involving murder. Example : "The man committed homicide and was arrested and jailed."
The witnesses and the victims.
Once a crime has been committed and reported, an investigation is started. Review the case, interviewing the victim, making sure the crime actually did happen, and analysis of the facts of the case are all the beginning steps of investigating a crime.
The forensic team were at the scene of the crime investigating.