Words can be powerful weapons, especially when they come from an enforcement agency or a regulator. And the announcement by the U.K.’s Serious Fraud Office (SFO) that it is investigating Rio Tinto’s activities in Guinea has called into question the effectiveness of the company’s anti-bribery controls and its leadership, particularly as two members of its executive committee have been forced out.

Neil Hodge is a freelance business journalist and photographer based in Nottingham, United Kingdom. He writes on insurance and risk management, corporate governance, internal audit, compliance, and legal...