"We can see how criminal networks start up businesses in cash-based industries," Stockholm County Police Commissioner Carin Götblad, tells Swedish Radio News. "Cash is a must for them to continue committing other crimes."
The police believe that most of the money is used for drugs, weapons and in some cases human trafficking.
But there are ways to prevent your money from being used to commit crimes.
Sofia Sjöström, head of the dry-clearers trade organisation Tvätteriförbundet, says that if a deal is too good to be true it probably is.
"If you leave five shirts and it only cost you 100 Swedish crowns ($15) then you know it is black money," Sofia Sjöström, head of trade organisation Tvätteriförbundet.