What term describes information that suggests further investigation is needed?

The term that indicates information suggesting that further investigation is needed is "lead." In the context of criminal investigations, a lead is a piece of information or a tip that directs investigators to follow a particular line of inquiry. Leads can arise from various sources, including witness statements, forensic evidence, or prior intelligence, and they often point to potential suspects, locations, or other aspects that require more thorough examination to advance the investigation.

In contrast to leads, evidence refers to material that is used to prove or disprove aspects of a case; it tends to be more definitive and is used as part of the legal process. A clue, while similar in nature to a lead, is often more vague and may not point directly to the next steps in an investigation. An indicator can suggest a trend or condition related to the case but lacks the direct actionable quality of a lead. Hence, "lead" specifically captures the notion of information requiring further exploration, making it the most appropriate term in this context.