When Nuhu Ribadu, Nigeria’s former anti-corruption chief, launched high-profile cases against venal politicians, his earlier campaign against ordinary conmen fell out of the limelight. Mr Ribadu was the first Nigerian police officer to win mass convictions for the e-mail scams that lure greedy and unsuspecting targets into millions of dollars of losses around the world, causing untold damage to legitimate Nigerian business.

The Economic and Financial Crimes Commission (EFCC) he chaired was set up by former president Olusegun Obasanjo as an urgent response to the chronic failure of other institutions: the police, public prosecution and judiciary. Arguably, it has provided the biggest gains in cleaning up Nigeria since the military handed back power to civilians in 1999.