Two paintings by French Impressionist master Pierre-Auguste Renoir, stolen from a museum in southern France last month, have been recovered after being hidden behind a wall, with both artworks sustaining minor damage, prosecutors said on Monday.

The paintings, valued at 4.2 million euros ($4.7 million), were discovered on Thursday during a search of a house in Clermont-l’Herault, southern France, Marseille prosecutor Nicolas Bessone told reporters in Paris.

The recovered works are Portrait of Madame Colonna Romano and Young Woman at the Well.

Thieves broke into a museum in Cagnes-sur-Mer last month and stole four paintings, abandoning two as they fled. Six people, including a woman, were arrested on Wednesday as part of the investigation, with authorities saying the suspects had been planning another art theft.

Investigators accelerated the arrests after the main suspect conducted a reconnaissance visit to the Fondation Maeght in Saint-Paul-de-Vence, which houses one of Europe’s largest collections of modern art.

“We were very clearly looking at the repetition of a criminal scheme,” said Eric Antonetti, head of the Alpes-Maritimes judicial police.

The two key suspects include a 29-year-old man who was charged after investigators recovered DNA from a bag abandoned during the getaway. He had previously been under investigation for drug trafficking, said Christian Sainte, head of France’s national judicial police.

Paintings concealed behind solid wall

The stolen artworks were hidden behind a solid cinder-block wall and remained undetected during an initial search of the property.

“They were completely undetectable,” Bessone said, adding that police returned to the house after obtaining a confession.

During the first search, investigators had examined the walls for hollow spaces, Sainte said.

Both paintings were recovered in relatively good condition, although they showed signs of damage, according to Bessone. The frame of Young Woman at the Well was slightly damaged, while Portrait of Madame Colonna Romano sustained a tear in the canvas around the dress.

Both works will require restoration, the prosecutor said.

Authorities believe the suspects acted without a buyer or sponsor. The paintings were found at the home of one of the suspects in Clermont-l’Herault.

The four men under formal investigation are aged between 29 and 51, and three have previous criminal convictions. Two remain in custody.

Culture Minister Catherine Pegard praised the efficiency and determination of those involved in recovering the paintings, with the culture ministry saying their efforts had enabled the works to be retrieved in record time.

The recovery comes amid growing scrutiny of security at French museums following a series of high-profile art thefts, including a daylight robbery at the Louvre in Paris last year.

Crown jewels valued at around $100 million were stolen from the Louvre in a seven-minute heist. Although all four suspected robbers have been arrested, the stolen jewels have yet to be recovered.