They first make some magnetic coins by melting copper wire.

Then, a special chemical is prepared, using shampoo, sanitiser and hand wash. This mix's job is to draw colourful marks on the coins. The coins are also dressed up with some interesting symbols.

Finally, they spread the news that some rare coins have been found in some remote area of the country among collectors, who work themselves up to a frenzy over the prospect of securing the coins.

When anyone shows interest to buy the coins, the syndicate calls them over for a meeting at luxurious hotels in the capital, to set the stage for their exorbitant demands.

They plan the conversation so well that the interested buyer is convinced that the coins are real.

They also convince the buyer that the coins are worth more than crores according to international standards.

The syndicate then bring out their ace. They tell the interested buyer that there's another buyer -- who is one of the syndicate's members, posing as a foreign coin collector -- who is willing to jointly buy the coins.

The syndicate then asks for advanced payment, to be split by the two buyers.

But as soon as the victim pays their share, the syndicate members simply disappear.

Using this very script, the syndicate has made over Tk 3 crore over the last couple of years,

Police's Detective Branch (DB) claimed to have unearthed this information after arresting four of its members from Manikganj and Dhaka in a special drive over the last two days.

The arrestees are Saiful Islam alias Bishnu, Saidul Islam Jihad, Sayed Mustakin and Matin Molla.

Police recovered around Tk 11 lakh and 42 different types of copper coins from their possession, said Mashiur Rahman, deputy commissioner of DB police.

He also said all of the arrestees are accused in several cases.

The syndicate has around eight to nine members, who worked in three groups.

The first group is led by Saidul, who worked on spreading news of the discovery of the coins.

Saiful, the leader of the second group, acted as the one who came across the coins while working at his farm or bamboo field.

The third group is led by Mustakin, who poses as an interested foreign buyer, investigators said.

DC Mashiur further elaborated their process. After the target is brought in for the meeting, Mustakin -- under the pretense of being a foreign coin collector -- comes in and says he has brought a chemist to check the authenticity of the coins.

This is when another syndicate member walks in dressed up as a chemist.

He checks the coin using some machines and approves of the coins' authenticity.

After this, the bargaining reaches a point where Mustakin offers to buy the coins jointly with the target collector, saying they can resell for higher sums.

He then pretends to only have a portion of the money, asking the victim to pay the rest.

But once this money is paid, all contact is severed with the victim.

The Daily Star obtained some footage of the syndicate members' activities and minutes from the staged meetings.

DC Mashiur Rahman said they are now trying to arrest the other members of the syndicate.

"People need to be cautious while making this type of deals as they can turn out to be fraudulent," he said.