After losing a series of high profile cases, the UK government has suffered yet another embarrassing failure in its efforts to hold white collar criminals accountable for financial fraud. But this time, instead of displaying a casual indifference toward crimes committed by the wealthy or an ineffectual prosecutorial strategy, the National Crime Agency (the UK's equivalent of the FBI) has been tainted by allegations of corruption. The Wall Street Journal reported Thursday that the NCA is conducting an internal probe into allegations that one of its employees leaked information to members of a European insider trading ring that undermined its own probe - the latest black eye for the agency as it seeks to ramp up its prosecution of financial crimes.

NCA

The NCA's internal corruption unit is looking into whether a government translator who had access to wiretap recordings tipped off the target of an investigation to try and disrupt the probe.

NCA

A spokesperson for the NCA, which was set up in 2013 to help bolster the government's prosecution of financial crimes in the wake of the crisis, refused to confirm or deny whether the rumor was true. As we've noted in the recent past, the Financial Conduct Authority, one of the agencies tasked with bringing insider trading cases, has an abysmal record with putting criminals away. The FCA has opened 172 insider-trading cases since the 2014; only three have resulted in regulatory action. Even when the agency is successful, the cases typically take years to prosecute. A conviction won against two bankers in 2016 stemmed from trading activity that took place between 2006 and 2008.

Though the name of the translator was not released, the details behind the investigation sound like something ripped from a premium-cable crime drama. For example, the NCA was tipped off about the moles by one of suspects, who wrote himself a letter explaining how the insider trading ring had been aided by "three people working for him" from within the NCA.

One of the suspects in the alleged insider-trading ring wrote a letter to himself that he hid under a carpet in his home before his arrest. In the letter, reviewed by The Wall Street Journal, he described how another suspect told him of a joint NCA investigation with the FCA into their trading.

The other suspect told him he had "three people working for him at the agency," according to the letter, referring to the NCA.

That suspect told him that a translator working with investigators contacted him through a party known to both of them, according to the letter and people familiar with the matter. The translator tipped him off about the investigation and subsequent discoveries by investigators, including what the other suspect was saying on the phone, the letter and people said.

The other suspect said that they could pay off NCA officers working on the case by transferring money to a bank account in Macau, according to the letter.

This embarrassment follows closely on the heels of the FCA's latest failed insider-trading prosecution: Earlier this month, the trial of a former UBS compliance officer who fed information to a notorious day trader ended in a hung jury.