Burglars have stolen medals and jewelry from the Stasi Museum in Berlin.
Berlin, Germany CNN  — 

Thieves targeted Berlin’s Stasi Museum on Sunday evening, making off with historic jewelry and medals relating to the secret police in the former East Germany.

The suspects broke in through a first floor window, smashing several exhibition cases and stealing artifacts, Berlin Police told CNN.

A museum employee discovered the break-in at around 10.40 a.m. local time on Monday. It is unknown how many suspects are involved; the State Criminal Investigation Office is now investigating.

The burglary came less than a week after raiders stole around 100 priceless treasures from the German city of Dresden’s Green Vault, one of Europe’s largest collections of art masterpieces.

The suspects smashed a display case, fleeing with diamonds, pearls and rubies. Police believe four thieves were behind last Monday’s dramatic heist but have so far found no trace of them.

Officials are offering a €500,000 ($550,000) reward for information regarding the break-in.

The monetary value of the Stasi Museum haul is unknown. But it has a high museum value, the museum’s director, Jörg Drieselmann, told German newspaper Tagesspiegel.

It includes several historic medals, including a Karl Marx Order, which was the highest award given in former East Germany, a Lenin Order and the Order of the Hero of the Soviet Union, Drieselmann told the newspaper.

The director added that the stolen jewelry included gold wedding rings, a watch, and a bracelet, which the Stasi acquired during its reign of fear from the 1950s until the fall of the state in 1990.

“It is always painful when a break-in occurs,” Drieselmann said. “The feeling of security is considerably disturbed.”

Correction: This story has been updated to correct the reward amount in euros.