Which investigative resource should not normally be used in a proprietary gambling investigation?

In a proprietary gambling investigation, telephone surveillance typically raises significant legal and ethical concerns that make it less suitable than other investigative resources. Laws governing electronic communications can be stringent, and in many jurisdictions, obtaining consent for telephone surveillance can be challenging or outright impossible. This creates a risk of legal repercussions, such as violations of privacy rights and potential criminal liability for the investigators.

In contrast, closed-circuit TV cameras, undercover operatives, and physical surveillance are more commonly accepted and practiced in investigations of this nature. These methods can provide valuable insights into the operations and behaviors within the gambling establishment without infringing upon the legal protections surrounding private conversations. They enable investigators to gather necessary evidence while typically adhering to established laws and protocols.

Overall, the limitations and potential legal issues associated with telephone surveillance make it a resource that should not usually be employed in these types of investigations.