Police have ended their investigation into the fire that devastated Shuri Castle in Naha, Okinawa Prefecture, last autumn, without identifying the cause.

The fire was not caused by arson, negligence or other reasons for which a criminal liability can be established, according to a report on the investigation results disclosed Wednesday by the Okinawa Prefectural Police.

The police closely investigated the northeastern section of the Seiden main hall, which burned furiously, and scrutinized metal fragments that are believed to be burned electric wiring.

With no signs of a short circuit found, the police could not conclude that the fire occurred due to a problem with an electric system.

No intruder was seen on video footage from 68 security cameras in Shurijo Castle Park. The police found no evidence of negligence related to the fire.

The fire, which occurred Oct. 31, completely destroyed Seiden and heavily damaged other buildings.

Naha’s fire department also completed its investigation without identifying a cause.