The accused used to extort money from foreign nationals in the form of Bitcoins and gift cards after telling that their details have come up in a case of crime, they said.More than 90 digital devices have been seized, along with Rs 4.5 lakh in cash. The accused have duped more than 3,500 people of around Rs 70 crore, police said.Police got information that an illegal call centre is being operated from the Peeragarhi area and that those working there targeted foreign nationals, a senior officer said.

'Thereafter, a raid was conducted and 42 persons -- 26 men and 16 women -- were arrested,' Deputy Commissioner of Police (Cyber) Anyesh Roy said.During interrogation, the accused disclosed that they contacted foreign nationals impersonating personnel of various law enforcement agencies and other government agencies such as the Social Security Administration, the Drug Enforcement Administration (DEA) and the US Marshals Service, he said.

They used to tell them that their bank accounts and other assets are being frozen as their details have been found at a crime scene and that there are bank accounts running in their names using which illegal transactions have been made to drug cartels in Mexico and Colombia, the DCP said.They also threaten the victims with immediate arrest, police said.The accused used to give the victims two options, either take legal action or go for an alternative dispute resolution, which they said would be faster and easier, police said.

When the victim chose to go for dispute resolution, the accused asked them to share financial details such as bank account numbers and the amount of money in those accounts, they said.Police said that the victims were told that the only way to safeguard their finances was to either buy Bitcoins or gift cards with their entire money in their bank accounts.In the case of Bitcoins, these were transferred to wallets operated by the call centre. The victims were told that these were safe government wallets, the DCP said.If the victim agreed to buy gift cards, they were told to share the number of their cards and that these cards would be linked to their new bank accounts, the officer said.