Chandrakar, accused of masterminding the alleged ₹6,000-crore racket, was extradited from Oman as agencies pursue co-founder Ravi Uppal.
The Mahadev Online Book network allegedly operated through thousands of betting panels, mule bank accounts and hawala channels, with ED pegging linked transactions at ₹94,000 crore.
The probe includes allegations of payments to public servants and political links in Chhattisgarh, with former chief minister Bhupesh Baghel denying the charges.