YAPHANK, N.Y. (CBSNewYork) — Drug dealers have found a new way to avoid getting prosecuted if selling drugs.

As WCBS 880’s Sophia Hall reported Monday night, it is a loophole that drug dealers have discovered – which frustrates police, because in some cases, they have to free the suspects.

Suffolk County police Chief of Detectives Gerard Gigante said the dealers use analogues, or chemicals that appear to be fentanyl. But when the chemicals are tested in a lab, the molecular structure is not included in the list of illegal narcotics, and the suspect either faces lesser charges or is let go.

“To be able to update the law, and be able, if they can, to put a mechanism in place where the law is more easily updated, or have some kind of catchall in there that would include these analogues,” Gigante said.

Gigante said up to 80 percent of the department’s 30-plus average weekly opioid drug arrests involve fentanyl analogues and cannot be prosecuted.

“I think the most frustrating part is you know that this fentanyl is just as deadly, or maybe even more so, than other opiates out there – and yet we can’t charge that person,” he said.