After a months-long joint investigation with the Italian State Police (Polizia di Stato), Croatian police arrested four Croatian nationals on Wednesday, suspected of stealing priceless jewellery in a bold heist in Venice in January.

The pieces were stolen from a private collection of jewellery and valuable Indian artefacts, the Al Thani Collection, assembled by the Qatari Sheikh Hamad bin Abdullah Al Thani.

The jewels were put on display in a temporary exhibition at the Doge’s Palace in Venice. The entire collection is considered priceless, and artefacts stolen include a pair of platinum-and-diamond earrings worth more than $1 million, and a platinum-and-ruby broche valued at more than $2 million, Croatian police said in a press release on Thursday.

The four Croatians, aged from 43 to 60, were arrested at undisclosed locations in Zagreb and in the Istria region based on a European arrest warrant issued by a Venice court.

One of the men arrested, who is known to use several identities, is suspected of taking part in several large jewellery heists across Europe committed by the so-called Pink Panther criminal grup, and was also wanted by the Swiss police over his alleged involvement in the theft of 8 million Swiss francs worth of jewellery in March 2011 in Basel.

As part of the same investigation, a 54-year-old national of Serbia suspected of being a fifth member of the group was also arrested at the Tovarnik border crossing on the Croatia-Serbia border.

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