How do forensic scientist determine what exactly everything is

Forensic methods and techniques.

Explanation:

Forensic methods and techniques include preparing for the execution of the examination, the examination, the collection of objects and samples, the preparation of evidence for laboratory expert evaluation, the interpretation and reporting of evidence.

The purpose of these techniques is to gather evidence to establish the truth.

The main goals of forensics are the reconstruction of the crime, the identification of the suspects, the determination of the motive of the crime, the arrest of the suspect. Forensics research is based on biology, physics, and chemistry. Forensics is one of the most important categories of criminalistics today.