For most of the 2010s, Isabel dos Santos was widely reported as Africa's richest woman, with stakes in banks, telecoms and diamonds. In January 2020, a leak of more than 700,000 documents, shared with the International Consortium of Investigative Journalists and known as the Luanda Leaks, set out a different account. Dos Santos, a politically exposed person by virtue of her family's position in the Angolan government, was found by investigators to have moved hundreds of millions of dollars in public and state-company money into a network of more than 400 companies and subsidiaries spread across roughly 94 offshore jurisdictions.¹

What makes this case worth its own article in this series isn't the scale of the fortune. It's who helped build it. The leaked documents show that PwC, Boston Consulting Group, McKinsey and Accenture, among the most respected professional services firms in the world, provided advice, tax structuring and consulting services to dos Santos's companies for years, earning millions of dollars in fees along the way.² Portuguese law firms set up shell companies and moved money on her behalf.³ None of these firms were running her empire. Each one only ever saw its own piece of it, a tax strategy here, a corporate restructuring there, an audit somewhere else, and none of them, on the available evidence, ever stepped back and asked what the whole picture actually looked like.

This is the pattern worth sitting with if you run a small agency, conveyancing practice, accounting firm or jewellery business. In the biggest laundering cases this series has covered, the Singapore case, the Sydney apartment purchase, Obiang's shell company purchases, there's rarely one professional who saw everything and chose to look away. There's usually a chain of separate professionals, each doing a piece of legitimate-looking work, none of whom had the full picture, and several of whom, based on later reporting, didn't look very hard at the piece they did have.

In the dos Santos case, one PwC subsidiary suggested ways for a dos Santos retail company to reduce its tax bill by incorporating a holding company in a low-tax jurisdiction such as Malta or Singapore.² Reporting on the leaked documents also describes PwC accountants disregarding red flags about unusual movements of money between dos Santos entities, activity that experts say should have prompted closer scrutiny.⁴ A separate consulting firm helped run a jewellery business acquired with Angolan public money.⁵ Each of these engagements, taken on its own, might have looked like ordinary professional services work. Taken together, according to investigators, they formed part of a structure used to move public funds into privately held, family-controlled entities.

It's tempting to read this story and think it's a problem for the PwCs and Boston Consulting Groups of the world, not for a two-person conveyancing practice or a suburban jewellery store. The opposite is closer to the truth. Large firms at least have compliance departments, internal audit functions, and, eventually, the resources to investigate and respond once red flags surface, however imperfectly. A sole trader or small partnership usually has none of that. If a real estate agent, a solicitor and an accountant all handle separate pieces of the same transaction, and none of them talks to the others, or asks broader questions beyond their own narrow task, that gap is even easier to exploit and even harder for any one of them to notice.

This is also exactly why Tranche 2 brings real estate agents, lawyers, conveyancers and accountants into the same regulatory framework at the same time, rather than regulating just one profession and hoping it catches everything. AUSTRAC's own reasoning for expanding coverage to this group of professions was that they sit at exactly the points in a transaction, forming a company, transferring property, moving trust funds, where this kind of layering happens, and that gaps in oversight of any one of these professions leave the whole system exposed.

You don't need a scandal on the scale of Luanda Leaks to see this pattern locally. A common and mostly innocent version plays out like this: a client engages an accountant to set up a company or trust structure, engages a solicitor or conveyancer to handle a property purchase through that structure, and engages a real estate agent to find the property. Each professional deals directly with the client and rarely, if ever, talks to the other two. If the client's story doesn't quite add up, an unclear source of wealth, a company incorporated the week before settlement, funds arriving from an account nobody recognises, each professional might individually notice something slightly off, shrug, and assume someone else in the chain has already checked it.

That assumption is the vulnerability. Nobody else in the chain has necessarily checked anything. Each professional is required, under their own Tranche 2 obligations from 1 July 2026, to conduct their own customer due diligence, and one professional's due diligence doesn't discharge another's obligation.

Isabel dos Santos did not amass a multi-billion dollar fortune by convincing one professional to hide everything. According to the Luanda Leaks investigation, she engaged dozens of separate, well-regarded firms for narrow, plausible-sounding pieces of work, and relied on the fact that none of them was looking at the whole picture.⁶ That is not a uniquely large-scale problem. It is the same structural gap that a small Australian real estate agent, conveyancer or accountant can just as easily become part of, one narrow, individually reasonable-looking engagement at a time.

The next article in this series looks at a UK enforcement mechanism designed to examine an individual's overall pattern of asset holding in a single proceeding: the Unexplained Wealth Order, and the case that first tested it, Zamira Hajiyeva's spending at Harrods.

Next in this series: "Case Study: Unexplained Wealth Orders in UK Property Transactions."