I need custody help for a few paragraphs for each question for my legal homework

(2a) The chain of custody establishes the case from the onset. Without it, the physical evidence is worthless. No amount of investigative skill will change this.

Please respond to the following prompts:

• Discuss the responsibilities of the first responder from the initial call until the crime scene is released. Include the transition from the first responder to the lead investigator.
• Define the chain of custody. Where does it begin?
• Why is the chain of custody important to all personnel associated with the investigation?