The scheme lured the investors offering extraordinary returns of 10% per month in Bitcoin over an 18-month period urging them to purchase the digital currency from external exchanges and deposit it with GainBitcoin through “cloud mining” contracts, the central agency said.The CBI on Tuesday conducted coordinated nationwide searches at 60 locations as part of its probe into the `6,600 crore GainBitcoin cryptocurrency scam, officials said.The searches were spread across multiple cities including Delhi NCR, Pune, Chandigarh, Nanded, Kolhapur and Bengaluru, targeting premises allegedly linked to key accused individuals, a CBI spokesperson said in a statement.The ponzi scam perpetrated through a web of platforms, including flagship site http://www.gainbitcoin.com, was allegedly masterminded by Amit Bhardwaj (now deceased) and his brother Ajay Bhardwaj, the officials said.Launched in 2015, the illicit operation was camouflaged under the facade of Variabletech Pte. Ltd, they said.The scheme lured the investors offering extraordinary returns of 10% per month in Bitcoin over an 18-month period urging them to purchase the digital currency from external exchanges and deposit it with GainBitcoin through “cloud mining” contracts, the central agency said.“The model followed a multi-level marketing (MLM) structure, commonly associated with pyramid structured ponzi schemes, where payouts were dependent on bringing in new investors,” the spokesperson said. “In an attempt to cover up losses, GainBitcoin unilaterally switched payouts to their alleged in-house cryptocurrency called MCAP, which had significantly less value than Bitcoin, further misleading investors,” the statement said.© The Indian Express Pvt Ltd