Ryan Knudson

And Chinese money launderers have learned to take advantage of that slowness.

But even when a bank does flag suspicious activity, there are so many reports that authorities usually don't look at it.

And it rarely sparks an investigation.

Dylan says the reports usually get thrown into a database that cops might check after they get a tip.

It seems like this case sort of shows, at least from the banking standpoint, that the safeguards that have been put into the system actually don't really work that well.

For years, Zhang and his network allegedly exploited these vulnerabilities in the banking system.

And over time, law enforcement began to take notice.

How Julie and a team of investigators slowly built that case against Zhang is next.

In cases that involve a vast criminal enterprise, such as money laundering, investigators have traditionally relied on a tried and true technique, wiretapping.

But in the Fortune Runner case, wiretapping wasn't an option.

That's because many Chinese money launderers rely on encrypted messaging apps like WeChat to do business.

You can't get a wiretap on WeChat.

So if you can't do a wiretap, you've got to do some legwork.

If Julie and her team wanted to break up Zhang's alleged scheme for good, she says they needed to draw a direct line between his business and the cartel's.

Then, in 2021, the investigators got a breakthrough when two money handlers were seen crossing the border.

The photograph is grainy.

It was in black and white.

The kind of photo you can expect from security footage.

It shows a car with one of Zhang's associates in the driver's seat.

And next to him, in the passenger seat, there's another man, a money handler associated with one of the most powerful drug cartels in the world, the Sinaloa cartel.