Florida authorities can be so accommodating – so much so that when Douglas Peter Kelly phoned sheriff's deputies to tell them he'd been sold the wrong illicit drug, they offered to test it for him.

Mr Kelly, from Hawthorne, called the Putnam County Sheriff's Office on Tuesday to say that he had bought what he thought was methamphetamine; but, after smoking it and having a "violent reaction," he suspected that he'd been given the wrong substance – and he wanted to press charges against the person who sold it to him, deputies said in a Facebook post.

Detectives told him they could certainly test the drug for him to ensure it was meth. And, the authorities said, he took them up on it.

"In an effort to ensure the quality of the drug the suspect purchased, detectives told Mr Kelly if he came to the sheriff's office they could test the narcotic he had purchased," said the post from the Putnam County Sheriff's Office.

"Mr Kelly drove to the sheriff's office and handed detectives a clear, crystal-like substance wrapped in aluminium foil. The substance field-tested positive for methamphetamine, the drug Mr Kelly intended to purchase."

Mr Kelly was arrested.

The 49-year-old was charged with possession of methamphetamine and was "walked" over to the jail, according to the Facebook post. His attorney could not be immediately reached for comment.

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Authorities in other states have made similar overtures. In May, the Gratis Police Department in Ohio posted a "warning" on Facebook about meth that could be contaminated with the Zika virus and offered to test it – gratis.

The post read:

"WARNING: If you have recently purchased Meth in Preble, Montgomery, Darke or Butler Counties it may be contaminated with the Zika Virus. Please bring it to the Gratis Police Department and we will test it for free. If you're not comfortable coming into our office, please contact us and we'll test your Meth in the privacy of your home."

It included a disclaimer: "Methamphetamine can't be a host for the Zika virus."

The Putnam County Sheriff's Office in Florida said in its Facebook post on Wednesday that deputies will test any suspected "bad drugs" for free.

"Remember," the post read, "our detectives are always ready to assist anyone who believes they were misled in their illegal drug purchase."