The Louvre remained closed Monday, a day after historic jewels were stolen from the world’s most-visited museum.

Paris is still coming to terms with the fact that thieves have scootered off with France's Imperial jewels.

Inside the Louvre's Apollo Gallery forensic teams have been scouring every inch for clues which could lead them to the raiders who got in - and out in around four minutes.

Eight objects were taken, according to officials: a sapphire diadem, necklace and single earring from a matching set linked to 19th-century French queens Marie-Amélie and Hortense; an emerald necklace and earrings from the matching set of Empress Marie-Louise, Napoleon Bonaparte’s second wife; a reliquary brooch; and Empress Eugénie’s diadem and her large corsage-bow brooch, a prized 19th-century imperial ensemble.

One object, the emerald-set imperial crown of Napoleon III’s wife, Empress Eugénie, containing more than 1,300 diamonds, was later found outside the museum, French authorities said.

For hours after the robbery the mechanical lift the robbers used to gain was left in plain sight, it was an obvious weakness that such large machinery could be brought onto the museum's grounds.

It all happened just 250 meters (270 yards) from the Mona Lisa.

According to Art Recovery International headquartered in London, police will now be questioning anyone who had previous links to jewellery and art thefts, as well as their associates and they will be checking informers.

According to Christopher A. Marinello a lawyer and art theft investigator for Art Recovery International the police and the gallery's experts will be desperate to catch the haul before it's split up and the stones have been extracted from their settings.

He says the police have already sought outside help: "They have admitted that they reached out to, CGI, an Israeli private investigative firm, to assist them in the investigation. In fact, that firm was successful in, helping arrest the criminals from the 2019 Dresden Green vault theft."

In 2019 thieves smashed vitrines in Dresden’s Green Vault, one of the world’s oldest museums, and carried off diamond-studded royal jewels worth hundreds of millions of euros.

Officials said they made off with three “priceless” sets of 18th century jewellery that would be impossible to sell on the open market.

Part of the haul was later recovered. Five men were convicted and a sixth was acquitted.

The Louvre's alarms brought agents to the scene of the crime on Sunday but by then the thieves had bolted.

Marinello is convinced the collection will be smuggled out of the country as soon as possible, but he doesn't believe the robbers want to sell the jewellery intact.

"I have never seen a theft to order case. You know despite Hollywood making us believe that there was some sort of secret collector Doctor No type out there. These criminals are just looking to steal whatever they can. They're just common thugs. They planned this very well, and they're not unintelligent, but, they are common thugs. And they chose this room because it was close to a window. They chose these jewels because they figured that they could break them apart, take out the settings, take out the diamonds and the sapphires and the emeralds and take them to Israel, take to Antwerp, India find a dodgy dealer that's willing to recut them and no one would ever know what they did," says Marinello.

He agrees that the collection as a whole is priceless, but he says the thieves will want to get as much cash as they can as fast as they can and the stones are still extremely valuable outside of the settings.

"As a piece, as as the remnants of the French crown jewels, they are priceless. But the thieves don't look at it that way."

"From my experience in recovering jewellery and watches and rare automobiles, they get stolen. Sometimes we have GPS in these items and we find them in certain countries in Eastern Europe. And, ask the police to cooperate. We're not always getting the the cooperation we need, but, there is a tendency for them to be Eastern European gangs throughout Europe right now," he adds.

Of one thing the thieves can be certain, every port and stretch of water will be watched.

And if Marinello is right and all signs point east, Interpol will be on the ground scouring every known jewel dealer and their associates.

Security measures at the Louvre had been strengthened in recent years and were being reinforced further as part of the museum’s upcoming overhaul plan.

Officials said security upgrades include new-generation cameras, perimeter detection, and a new security control room. But critics say the measures come far too late.