Four security guards are under investigation for their alleged roles in one of the largest European jewelry heists in recent history.

Investigators and German prosecutors believe that accomplices inside the historic Green Vault in Dresden helped carry out the heist of priceless jewels. The theft took place on the morning of November 25, when two intruders broke into the museum through a small window, smashing the glass cases to steal the jewelry, and then taking off in a getaway car. The loot has been estimated to be worth as much as $1 billion.

The two security guards on duty did not “react adequately” in failing to prevent the theft, according to investigators.

Another two security guards who were not on duty that evening may have helped the thieves. Prosecutors allege that one guard, who was arrested on November 29, had passed on information about the museum’s layout and security system to the perpetrators. Authorities have searched the apartment of the fourth security guard who prosecutors suspect of meddling with the alarm system. On the night of the robbery, a fire broke out at an electrical distribution point that deactivated the museum’s electricity and its alarm system.

It is now believed that a total of seven people carried out the theft. The police have released a sketch depicting one of the suspects they believe was involved in the robbery.

Police sketch of the man believed to have purchased the Audi S6 used in the Dresden Green Vault Heist. Courtesy of Saxon Police Department.

Police have also discovered more information about the getaway car. The 2006 Audi S6 was purchased by an unknown person in August 2019 from a private seller in Magdeburg. The buyer was about 25 years old and a police sketch has been released to the public. The investigators are assuming that this buyer is connected to the subsequent burglary. The burnt out car was found in a parking lot not far from the museum.

Authorities are offering a €500,000 ($571,517) reward for treasures, which included three sets of diamonds and other precious jewels, the majority of which were acquired by Augustus the Strong and Augustus III and date to between 1782 and 1789. Since November, police have received 1,300 tips from the public. Last month, there were reports that the jewels were circulating on the dark web.