Final answer:
A single investigator typically uses a spiral search pattern to search a crime scene methodically and efficiently, helping to ensure no evidence is overlooked.
Step-by-step explanation:
The type of pattern used by a single investigator when searching a scene is typically a spiral search pattern. This approach allows the investigator to begin at a certain point and move outward in a spiral manner, which is efficient for ensuring that the entire scene is methodically searched without missing any potential evidence. It is a common method used in situations where one investigator is responsible for covering the whole scene.