Investigators say the four suspects in last month’s Louvre heist are local petty criminals with no links to organized crime.

The group—three men and one woman—lived in or around Seine-Saint-Denis, a suburb north of Paris, and had prior convictions for robbery and other crimes.

One man had 11 previous convictions, another 15, and two were involved in a 2015 Paris robbery; one man is in a long-term relationship with the female suspect.

Prosecutor Laure Beccuau noted that while the suspects are not connected to organized crime, people without such ties are increasingly committing serious offenses, CNN reported.

On October 19, the thieves used a truck-mounted ladder to access the Louvre’s Apollo Gallery and stole nine pieces of French crown jewels, including a diamond and sapphire set worn by Queen Marie-Amélie and Queen Hortense.