‘Why didn’t that baby die?’: Teen allegedly tried to kill brother’s daughter by poisoning breastmilk

A US woman has been charged with attempted murder after she allegedly plotted to kill her brother's 11-week-old daughter with poisonous breast milk.

Sarai Rodriguez-Miranda, 19, from Indiana, was investigated when her mother discovered disturbing text messages on the phone they shared, the Journal Gazette reports.

Speaking to her boyfriend via text message, Rodriguez-Miranda allegedly said "I'm gonna crush up some of these pills since she decided they can stay longer and kill their baby" after her mother let her brother, his fiancée and their newborn live at the house.

“I put the stuff in a made bottle in the fridge,” she allegedly wrote.

“Yeah I thought it was funny that I don't have an ounce of guilt.”

Once she discovered the messages, her mother went to examine the bottles and found the breast milk was an off color, authorities said.

She took the baby to the hospital.

It was found that she didn't show any signs of poisoning.

Police confiscated evidence in the matter including suspicious bottles, and a mortar and pestle that was covered in a white, powdery substance.

The substance was found to contain acetaminophen, caffeine and aspirin, the ingredients in headache relief tablet Excedrin.

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According to the report, one bottle contained the equivalent of nine Excedrin tablets, which is enough to kill an adult, the New York Post reports.

“Why didn’t that baby die dude, that's dumb,” she allegedly wrote.

By the time police wanted to interview Rodriguez-Miranda, she had fled to Michigan with her boyfriend.

A warrant has been issued for her arrest.

Her bond is US$50,000.