Kim Kardashian West's Paris robbers were inside her apartment for 49 minutes prior to holding her at gunpoint.
A police source claims the group of men, who raided the 35-year-old beauty's apartment in the French capital and stole $10 million worth of jewellery, "knew the security code" to the property.
The insider said: "They acted like they had all the time in the world. It is quite incredible that they managed to hang about for so long without anyone calling us."
They also state that three of them arrived at 2.18am and CCTV footage showed it wasn't until 3.07am that the five of them departed the building.
Talking about three of the suspects, who wore dark clothing, the insider told Us Weekly magazine: "They clearly knew the security code of the main doors, and let themselves in without any problem at all."
The 'Keeping Up With the Kardashians' star's lawyer says Kim is "very calm and very determined" to help catch those responsible.
Jean Veil said: "She is very calm and very determined over a matter that was particularly violent.
"If she is summoned to France. she will come to France, but judges also have the possibility of moving [to the United States]."
Meanwhile, it was previously reported that the fivesome used a decoy to escape.
Police investigating the theft reportedly discovered a tiny gemstone close to the residence, which they thought might have been used to make police "believe that they were amateurs".
A police official previously told the publication: "They wanted us to believe that they were amateurs, but all the real clues point to them being extremely sophisticated professionals. There is no way a gang like this would drop stuff and fall off bicycles -- all that was done for any cameras that might be in the area. It is far more likely that they played around on bikes for a few minutes after stealing the jewels, and when they still had their masks on, before they all got into a van and disappeared."
Kim - who has children North, three, and Saint, 10 months, with husband Kanye West - is still very nervous following the robbery and has been unable to be alone since returning to the US hours after the raid.
A source previously said: "Kim is completely shell-shocked and has told her family that her life has changed forever. She is jumping at the smallest sounds and can't be alone at the moment."
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