The Customs Intelligence and Investigation Directorate has asked the central bank to provide information on transactions made by Apan Jewellers' owner Dildar Ahmed.
CIID Director General Moinul Khan said they wrote to the Bangladesh Bank on Thursday seeking detailed information.
A committee has been formed to check their transactions, he added.
“We will try to find out how Dildar collected the gold he is selling, despite the fact that there has been no gold import for 10 years,” Moinul added.
CIID sources said the Customs Intelligence decided to investigate Dildar after social media users raised allegations of gold smuggling against him. He owns gold shops at Uttara, Gulshan and Mouchak in Dhaka.
Dildar's son Shafaat Ahmed and two others have been accused of raping two university students at a Banani hotel in March. Shafaat, who went into hiding after the case was filed last week, was arrested in Sylhet on Thursday.
Shafaat reportedly was outspoken in admittting that his father used to collect gold from the seized consignments while threatening the rape victims.
CIID chief Moinul said allegations of Dildar being involved in murky business transactions were old. They resurfaced recently in the mainstream and social media.
“We will try to find out how he became so rich,” he said.
“We will also check whether the diamonds being sold in his shops are real, and if they are being traded transparently and if a duty has been paid properly,” he added.