Which term designates a person who is no longer present and not known to be safe?

The term that designates a person who is no longer present and not known to be safe is "Missing Person." This designation is specifically used in law enforcement and public safety contexts to refer to an individual whose whereabouts are unknown and who may be at risk of harm or danger.

When someone is classified as a missing person, it typically triggers a set of protocols that law enforcement agencies follow to locate and ensure the safety of that individual. This classification can apply to various circumstances, including abduction, voluntary disappearance, or situations where a person cannot be reached or contacted, raising concern for their wellbeing.

In contrast, the other terms do not accurately describe the situation of someone missing and potentially in danger. A "Suspicious Person" refers to an individual behaving in a way that raises concern but does not indicate absence or a safety risk. "Check on welfare of" implies a specific action taken to ensure someone's safety, while "Security Check" usually refers to a systematic inspection or assessment of an area rather than the status of an individual.