Interrogator (noun)

1. A person who questions someone in order to obtain information or a confession.
2. A machine or device used for questioning or testing.

Origin:

Late 16th century (as an adjective meaning "questioning") from latin interrogat- "questioned", from the verb interrogare.

Examples:

1. The interrogator asked him many questions but didn't get any useful answers.
2. The interrogator at the border was asking for his passport and visa.
3. The criminal was interrogated for hours but refused to give any information.
4. The interrogator machine tested his knowledge on various subjects.
5. The police were determined to find the truth, so they brought in an experienced interrogator.