Bulgarian archaeologists have found a precious and unique piece of jewelry, more than 600 years old, which is believed to have been used by affluent males to execute political murders in order to gain more power.

The bronze ring features a small hollow space on the side to conceal poison that allowed its wearer to effortlessly pour the poison into an enemies' glass of wine or food without being noticed.  

The fourteenth century ring, a unique murder weapon was discovered during excavations in the ruins of Cape Kailakra, a place close to the town of Kavarna on the Bulgarian Black Sea coast. Along with the medieval ring, archaeologists also unearthed 30 other pieces of gold ornaments, gold rings and pearl jewelry.

Bonnie Petrunova, the dig leader and deputy director of Bulgaria's National Archaeology Museum, said that the ring may  have been brought in 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.

Petrunova also said that the discovery of the ring is the 'oldest proven case of serial murder.' It might help to provide answers to numerous strange deaths of politicians and nobles close to Dobrotitsa, a noble who ruled the region in the second half of the 14th century.