Bulgarian archaeologists have discovered a valuable piece of jewelry more than 600 years old, which is thought to have been used to commit murders of high-profile politicians.

A fourteenth century ring reveals the art of murder used by people during that period to skillfully do away with their political enemies and rivals. The imperative discovery was made at the site of a medieval fortress on Cape Kaliakra, a place close to the town of Kavarna on the Bulgarian Black Sea coast. Archeologists discovered 30 other pieces of gold and pearl jewelry from the site but found the small bronze ring more significant.

Archeologists believe that the medieval ring was used by wealthy power-hungry males of the region to gain more power by killing rival political aristocrats .

The ring is fully made of bronze with exquisite art crafted on it. It also features a small hole into the side, which was used to hide poison that can be easily poured into a glass of wine or food without anyone's notice. According to dig leader Bonnie Petrunova, deputy director of Bulgaria's National Archaeology Museum, the poison used in the ring was supposedly imported from Spain or Italy

"I have no doubts that the hole is there on purpose and the ring was worn on the right hand, because the hole was made in such a way so as to be covered by a finger, so that the poison can be dropped at a moment's notice. Clearly, it was not worn constantly and would have been put on when necessary," Petrunova said in a press statement.

She adds that the discovery of the ring is the "oldest proven case of serial murder." It may be the answer to several mysterious deaths of politicians and nobles close to Dobrotitsa, a noble who ruled the region in second half of the 14th century.