Hope Olusegun Aroke pulled off internet scams amounting to more than $1m (around R14.78m) while serving time for fraud.
According to the BBC, while serving a 24-year jail sentence in a Nigerian prison, Aroke had access to a cellphone and the internet.
Aroke got admitted to a police hospital, moved to a hotel, received guests and attended parties.
He used a fictitious name to open two bank accounts, and bought a luxury car and homes during his prison term.
The head of the prison and a prison doctor have been arrested.