The officials of the Customs Intelligence and Investigation Department (CIID) have further questioned the three owners of Apan Jewellers.
The interrogation, which took place on Sunday, was conducted for several cases of money laundering and tax evasion.
Earlier on Thursday, the accused - Dildar Ahmed and his brothers Gulzar Ahmed and Azad Ahmed - were placed on remand for a day so the interrogation could take place.
A Dhaka court granted the one-day remand after the CIID officials petitioned for a three-day remand for further questioning.
The trio were sent to jail on October 24 after they surrendered before separate courts, a day after warrants were issued for their arrests.
Earlier on August 12, the CIID sued the Apan Jewellers owners after 15 maunds of illegal gold and some diamonds were recovered from five of its showrooms in Dhaka.
Five CIID assistant revenue officers filed five cases – two with Gulshan police station, one with Dhanmondi police station, one with Ramna police station and one with Uttara police station – following directives from the National Board of Revenue.
Apan Jewellers came under the spotlight after the rape of two private university students by Shafat Ahmed, son of Dildar Ahmed, and his accomplice at the RainTree hotel in Banani.
Following CIID requests, the Anti-Corruption Commission has also launched its own investigation into the three owners.