A woman was arrested after police said she injected an unknown substance into her ill 19-month-old daughter's feeding tube.

Valeria Shakhov, 28, of Carroll, Iowa, was charged with felony child abuse after her arrest Friday. She declined to comment after a Wednesday court hearing.

Toxicology tests were being conducted to determine what the substance was. Shakhov told police the injection was formula, authorities said.

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The girl, Rachel Pineda, was hospitalized frequently with unexplained illnesses.

Police have said Shakhov suffers from Munchausen syndrome by proxy, a disorder in which a person causes a family member's illness to care for the person or be a hero by saving them.

Hospital workers called police after witnessing Shakhov continuously weigh her daughter, shut down her feeding tubes and ignore medical advice.

Police got a warrant to conduct video surveillance and hid a video camera in the girl's hospital room. It was through that surveillance that police said they saw Shakhov make the injection.

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