Culprit (noun)

1. A person guilty of a crime or an offence.
2. A person or thing that is responsible for a particular problem or fault.

Origin:

Early 17th century: from latin culpritus, from culpa "fault".

Examples:

1. The police arrested the culprit.
2. The culprit was caught on camera.
3. The culprit was found to be the faulty wiring.
4. It was difficult to determine who the real culprit was.
5. The culprit of the robbery was caught and brought to justice.