NEAH BAY, Wash. (AP) — A Washington police department is warning the public that officers believe they found fentanyl-laced marijuana during a recent arrest.

The Peninsula Daily News reports (http://bit.ly/2xrz6Jr ) Makah Tribal Police Department Public Safety Director and Police Chief Jasper Bruner says officers field-tested seized marijuana Friday and the test was positive for fentanyl, a synthetic opioid that can be 50 times stronger than heroin.

Bruner says the marijuana would be retested at the Washington State Patrol Crime Lab.

Officials at other agencies say they have never seen any confirmed reports of fentanyl-laced marijuana in the region or Pacific Northwest.

Though marijuana is legal in Washington, it is still illegal on the reservation, which operates under federal law.

Bruner wouldn't name the person who was arrested, but says the person is facing tribal charges.

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Information from: Peninsula Daily News, http://www.peninsuladailynews.com