David Balland, a co-founder of French crypto firm Ledger, had his hand mutilated while he and his wife were kidnapped, the Paris prosecutor said, adding that 10 people were being questioned following the freeing of the pair.

A co-founder of French crypto company Ledger and his partner have been freed after being kidnapped and held to ransom, the Paris prosecutors' office said on Thursday. David Balland was kidnapped early Tuesday morning at his home in central France and taken by car to another address where he was held captive,