Why is it important for a forensic investigator to be familiar with the different types of poisons? What are organic poisons and how might they be used in a crime scene?

Why is it important for a forensic investigator to be familiar with the different types of poisons? What are organic poisons and how might they be used in a crime scene?

please use the textbook below:
Criminalistics: Forensic Science, Crime, and Terrorism
4th Edition, 2018
ISBN: 9781284142617
James E. Girard
Jones & Bartlett Learning