The customs is interrogating three owners of Apan Jewellers over the cases of money laundering that were started against them in August.
Brothers Dildar Ahmed Selim, Gulzar Ahmed, and Azad Ahmed are accused in the cases.
The Customs Intelligence and Investigation Directorate or CIID started five cases accusing the three of depositing smuggled gold, making ornaments with them and selling them abroad.
They were also charged with hiding information of 570kg gold and diamonds in tax statements.
Police produced them at the directorate around 11:30am Sunday, CIID chief Moinul Khan told bdnews24.com.
Dildar is the father of Shafat Ahmed who has been arrested on charges of raping two university girls at a hotel in Banani. Four others, co-accused in the rape case, are also behind bars.
Dilar and his brothers were sent to jail following a court order on Oct 24, six months after the arrest of Shafat.