Investigator (noun)

1. A person who carries out an investigation or inquiry, especially into a crime or scientific matter.
2. A person appointed to inquire into a matter, especially an official appointed to investigate a crime or an accident.
3. A person who conducts research or makes a systematic inquiry into a subject.

Origin:

The word 'investigator' originated in the late 17th century from the latin word 'investigare' meaning 'to inquire into or examine.'.

Examples:

1. The investigator gathered all the evidence from the crime scene.
2. The investigator was appointed to inquire into the matter and find the truth.
3. The investigator conducted extensive research on the subject and published a groundbreaking report.
4. The investigator was a seasoned detective with years of experience in solving crimes.
5. The investigator was an expert in his field and was widely respected by his peers.