The recent actions of a McDonald's employee in Kansas are leaving a bad taste in the mouths of police officers and their supporters.

A Topeka employee at the fast food chain has been fired and is currently facing criminal charges after local law enforcement say the worker put mustard in an officer’s beverage.

On Friday, an officer with the Topeka Police Dept. says he went through the McDonald’s drive-thru at the 2000 block of NW Topeka Blvd. The officer—who has not been named—said his drink tasted funny and lifted the lid to find what appeared to be mustard squired inside, reports 13 NEWS.

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On Sunday, Kansas Going Blue posted a picture of the tainted drink on its official Facebook page. As of Tuesday morning, the photo has over 4,000 shares.

Tom Dobski, the franchisee owner of the north Topeka McDonald's where the officer found mustard in his Dr. Pepper, says the company is "shocked by the isolated actions of a single employee."

“All customers, including local law enforcement officers who protect and serve our communities, are always welcome at our restaurants,” Dobski said in a statement issued Monday. “We proudly support police officers and all divisions of first responders at our restaurants across northeast Kansas.”

After police complained, Dobski says the company launched an internal investigation immediately. He added that the employee responsible, whom he did not name, no longer works for McDonald’s.

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After discussing the incident with the District Attorney's Office, the Topeka Police Dept. say they have decided to open a criminal investigation. They added that Dobski is cooperating with with all queries.

The incident comes just two weeks after a Kansas Highway patrol officer reported similar incident involving mustard in his soda.