Traces of something like a liquid have been found on the Bussokuseki stone imprint of Buddha*s feet, a Japanese national treasure at Yakushiji Temple, a World Heritage site in the city of Nara, officers from the prefectural police said Tuesday.

Officers are investigating the case on suspicion of violation of the cultural properties protection law.

A temple staffer found four stains on the upper part of the stone imprint housed in the temple*s main hall at around 4 p.m. on Sunday, according to the police. Each spot measured about 1 to 2 square centimeters and had no detectable smell.

The stone imprint, the oldest existing Bussokuseki in Japan, was created in 753, according to the temple.