Lakeland, Florida - A Florida woman has been charges with three felony counts of animal cruelty after authorities say she fatally poisoned her neighbor's two cats and pregnant dog.

"It takes a cold-hearted person to poison and kill two cats and a pregnant dog," Polk County Sheriff Grady Judd said at a press conference. "It’s hard to imagine how a person in the medical field could do such a thing," He added.

On January 3, Florida officials arrested and charged Tamesha Knighten, a 51-year-old licensed practical nurse.

Per Sheriff Judd, the animals "were loved by their family."

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On August 16, the owners of a four-year-old pregnant Chihuahua named Daisy, and two cats, Luna and Pancake, called the police as their pets died horribly and suddenly, one by one.

The agriculture crimes unit took over investigating the case as it was clear the animals had been poisoned. Investigators "left no stone unturned," Sheriff Judd said.

It took months, and cooperation with the University of Florida, Texas A&M University, and Michigan State University to confirm that the pets were poisoned with Phorate, an insecticide.

Investigators also discovered insecticide in the bowl of food put out by Tamesha Knighten.

Daisy, Luna, and Pancake's humans told investigators that their neighbor, Tamesha Knighten, had previously threatened to poison their furry family members if they continued to come in her yard.

Sheriff Judd said Tamesha told detectives she put out a bowl of chicken with her "special seasoning" for the neighborhood animals. Surveillance footage shows Knighten putting out a bowl of what appeared to be food while wearing a plastic glove. Samples proved the food included the same pesticides found in the animals' bodies.

"This suspect, despite all evidence to the contrary, repeatedly denied killing her neighbor’s pets," Sheriff Judd said.

"Do not ever poison innocent animals," Sheriff Judd warned and added, "Unless, of course, you want to go to jail as well."