The Suffolk County District Attorney's Office dropped a felony drug charge Wednesday against a Mastic man after it said Suffolk police knew the white powder seized in connection with the case was not fentanyl. 

Prosecutors said lab tests showed 2 pounds of white powder that Homeland Security agents intercepted at John F. Kennedy International Airport intended for Corey Robinson was not fentanyl or any other controlled substance. Earlier field tests indicated that it was.

Police arrested Robinson and two other men last week.

The DA's office said the Suffolk County Police Department knew about the negative test results before going forward with the arrests.

"The substance field tested positive for fentanyl and subsequently was confirmed to be a fentanyl analogue, and thus was sent to another lab for further testing to identify the exact chemical structure," said Assistant Police Commissioner Justin Meyers in a statement released Wednesday. "The DA's Office was in consultation on the case each step of the way and knew these facts. Knowing this, the DA's office obtained the search warrant for the SCPD and instructed the SCPD to charge the case, which was the appropriate course of action."

Meyers also said that the packages were sent to another lab in Pennsylvania to be tested for analogs -- slight molecular variations of the drug. He added that the dropped charges were a "complete surprise."

"The drug still looks like fentanyl, acts like fentanyl, field tests like fentanyl and it's certainly still as lethal as fentanyl," he said. "We will continue to pursue this case. This is a good case that took hundreds of grams of lethal substance off the streets of Suffolk County."

People who spoke with News 12 at Robinson's home said they did not know when or if he would be back, and the DA's office said it had no one available to speak about the issue on camera.