follow the money

Popularized in the film All the President's Men (1976).

• "No, I have to do this my way. You tell me what you know, and I'll confirm. I'll keep you in the right direction if I can, but that's all. Just… follow the money."
• "Then follow the money: We know that President Bashar Assad turned an ophthalmologist's blind eye to Saddam's use of the Syrian port of Tartus to import missile fuel components from China and night-vision goggles from Russia."
• "His success in tackling and convicting members of Cosa Nostra was by following the money; this is the only way leading members of organised crime syndicates will ever be convicted."

• cui bono