HOUSTON (CBSDFW.COM/AP) — Harris County sheriff’s officials say initial test results were wrong and flyers found on patrol cars and other vehicles were not tainted with fentanyl.

Flyers laced with Fentanyl were found on Harris County Sheriff’s Office vehicles. (HCSOTexas/Twitter)

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Authorities said in a statement Friday that an initial test done on a flyer found Tuesday by a sheriff’s sergeant who later felt ill resulted in a positive finding for the opioid painkiller known to be more powerful than heroin.

But further testing was later done in a laboratory on 13 flyers, the sergeant’s clothing and other samples. All proved negative for the drug.

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The sergeant became ill after removing a flyer from her windshield and placing it inside her vehicle. She was treated and released at a local hospital after experiencing symptoms that included a tingling sensation, dizziness, impaired vision, and a headache. It’s not clear what caused her to become ill.

The flyers promoted a group whose website includes claims that the government is controlling individuals through microwave beams.

Fentanyl is an opioid commonly used to treat severe pain and can be deadly when taken in high doses.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)