A quadruple murder in Oklahoma shows how the Chinese underworld has come to dominate the booming illicit trade, fortifying its rise as a global powerhouse with alleged ties to China’s authoritarian regime.

Oklahoma has quickly become a top supplier of illicit weed. Although street prices fluctuate and calculating the value of a black market is complex, officials estimate the value of the illegal marijuana grown in the state at somewhere between $18 billion and $44 billion a year. State investigators have found links between foreign mafias and over 3,000 illegal grows — and they say that more than 80% of the criminal groups are of Chinese origin.

The federal response, however, has been muted. With the spread of legalization and decriminalization, enforcement has become a low priority for the U.S. Department of Justice, anti-drug veterans say.

“The challenge we are having is a lack of interest by federal prosecutors to charge illicit marijuana cases,” said Ray Donovan, the former chief of operations of the Drug Enforcement Administration. “They don’t realize all the implications. Marijuana causes so much crime at the local level, gun violence in particular. The same groups selling thousands of pounds of marijuana are also laundering millions of dollars of fentanyl money. It’s not just one-dimensional.”