The heist played out like a scene straight from a Hollywood thriller. In a maneuver as bold as it was brief, four masked burglars managed to slip into the Louvre’s Galerie d’Appollon during Sunday visiting hours on Oct. 19, executing a $100 million smash-and-grab before vanishing into the streets of broad-daylight Paris.

The timing would have impressed Danny Ocean himself: seven minutes flat, with the escape made before most visitors even realized a crime was underway.

The famous galleries reopened within three days, but the stolen jewels — and some of their burglars — remain missing. In a twist worthy of the 2006 mystery thriller The Da Vinci Code, the thieves’ haul included eight pieces from the famed royal jewelry collection: a sapphire tiara and necklace once worn by French royalty, an emerald necklace with matching earrings and the diamond diadem of Empress Eugénie, wife of Napoleon III.

Experts have valued the treasures at over $100 million.

Louvre Director Laurence des Cars admitted before the French Senate last week that there was a “weakness in the perimeter protection of the Louvre.” The only security camera guarding the balcony where the thieves entered was facing west, leaving the break-in site unguarded. According to investigators, the thieves disguised themselves as construction workers, using a truck-mounted ladder to cut through a first-floor window of the Galerie d’Appollon before fleeing on a scooter.

Des Cars emphasized that once the thieves breached the window, the Louvre’s security system functioned correctly. Alarms sounded and security staff quickly alerted police, but it was too late. Precious time and precious jewels had already been lost.

Adding intrigue to the mystery, prominent British newspaper The Daily Telegraph reported that detectives suspect the heist may have been an inside job aided by a security guard. Police are analyzing over 150 DNA samples and fingerprints collected at the scene, which were used to make two arrests on Saturday according to AP News. Five other suspects were detained on Thursday morning

So far, authorities have recovered only a single diadem, battered and damaged on the floor during the escape. The Louvre has rushed its remaining crown jewels to the vaults of the Bank of France for safekeeping.

Jewelry experts caution that while the robbers may have outsmarted the Louvre’s security, they have not outsmarted the market. Fencing the jewels will prove far more difficult, as authorities are on high alert. “Taken apart and sold as stones and metal, their value drops by 90 percent,” Parisian Jeweler Stephen Portier told CBS News. “The whole world knows about this robbery, so if they think they’re being offered diamonds from the Louvre they will ask some hard questions and contact the police.”

For now, the world’s most famous museum must answer an awkward and pressing question: how did four people with a ladder outwit the guardians of the Mona Lisa?