MUMBAI, March 11 -- Responding to an alert from the Mumbai immigration authorities regarding a pending Lookout Circular against him, the CBI on Tuesday arrested Ayush Varshney, co-founder and chief technical officer of Darwin Labs Private Limited, as part of its investigation into the multi-crore GainBitcoin crypto-currency fraud case. Varshney was taken to Delhi for interrogation. Describing him as a key accused, CBI officials on Wednesday said that Varshney's firm was instrumental in developing the entire technological infrastructure of the Bitcon-based fraudulent scheme run by a firm called Variabletech Pte Ltd and its promoters. The proceeds of crime in the case are estimated to be Rs.6,606 crore at 2017 rates. Bitcoin is a convertible virtual currency which is not legal tender in India. Its "mining" refers to the method used to produce new coins in this and other cryptocurrencies and examine new transactions. A crypto wallet is a software that allows access to cryptocurrencies. The CBI's investigation revealed the alleged roles of Darwin Labs Private Limited and its co-founders, including accused Varshney, Sahil Baghla and Nikunj Jain, in the scam. The central agency took over the investigation of all the police cases registered across India related to the alleged fraud following a Supreme Court order of December 12, 2023. The case pertains to the GainBitcoin ponzi scheme floated by Variabletech Pte Ltd, wherein investors were allegedly induced to invest in a crypto-currency scheme on the promise of high returns (10% monthly). The bitcoins collected from investors were meant to be used for bitcoin mining, and the investors expected lucrative returns in the mode of crypto assets. However, the promoters allegedly siphoned off the bitcoins and concealed them in obscure online wallets. The police cases, taken over by the CBI, were registered against Variabletech Pte Ltd , the late Amit Bhardwaj, Ajay Bhardwaj, Vivek Bhardwaj, Simpy Bhardwaj, Mahender Bhardwaj and several multi-level-marketing agents. They allegedly collected around Rs.6,606 crore in the form of 80,000 bitcoins from investors. In February 2025, the CBI seized crypto-currencies worth Rs.23.94 crore along with documents and electronic devices during its searches conducted in several cities including Mumbai, Pune, Nanded and Kolhapur in Maharashtra and the National Capital Region. The searches targeted premises linked to the accused individuals, their associates and entities suspected of laundering money. The Enforcement Directorate (ED)'s Mumbai unit is also conducting its own investigation into the case. There are at least nine overseas firms under the ED scanner, including those based in Hong Kong, Dubai and Estonia, which were allegedly used to divert the proceeds of crime in the case. In April 2024, the ED attached assets worth Rs.97.79 crore of businessman Ripu Sudan Kundra, also known as Raj Kundra, husband of Bollywood actress Shilpa Shetty. The ED probe revealed that Kundra had received 285 bitcoins worth over Rs.150 crore from the case's mastermind, the late Amit Bhardwaj, for setting up a bitcoin mining farm in Ukraine. As the deal had not materialised, Kundra was suspected of having the 285 bitcoins in his possession. However, he denied any wrongdoing, and told the ED that he had acted merely as a mediator and forfeited the amount since the deal did not work out. The agency filed three chargesheets against several accused persons in June 2019, February 2024 and September 2025 in a Mumbai special court. The September 2025 charge sheet was against Kundra and another businessman. Two key accused, Ajay Bhardwaj and Mahendra Bhardwaj, are still absconding....