Finnish police detained three suspects — and released one of them — in the unprecedented operation over the weekend, according to national media. The raid allegedly targeted a real estate firm chaired by a dual Russian-Maltese citizen.

A Russian national has reportedly been detained in Finland on suspicion of money laundering a day after large-scale police raids in southwest Finland.

A spokeswoman for the Russian Embassy in Helsinki told the RBC news website that the Finnish police had detained a Russian citizen as part of a money-laundering case.

“His identity is being withheld in the interest of the investigation,” the spokeswoman was quoted as saying.

The name of the targeted company was also kept secret, but Finland’s national broadcaster YLE cited eyewitnesses in reporting the searches took place at the Airiston Helmi company.

Property documents showed Airiston Helmi buying or selling 9.2 million euros of real estate in the southwestern Finnish archipelago of Turku in 2007–2014. YLE said records showed the firm selling a property in Pargas to a private buyer for 4.5 million euros. The firm reported losses of 300,000 euros last year, according to the broadcaster.

The Helsinki Times reported that a total of 17 premises in and around the town of Pargas were searched and seven people were interrogated over the weekend.

Senior Finnish National Bureau of Investigation (NBI) officer Markku Ranta-aho said it “will certainly take months” to comb through the documents and data storage devices seized during the raids.

In its announcement about the operation on Saturday, the NBI said it suspects “several million euros have been laundered within a Finnish limited company” with use of illegal labor.

The Finnish Security Intelligence Service (Supo) had reportedly closely monitored the Airiston Helmi real estate firm for years over its alleged ties to Russia.