A Fort Wayne, Indiana, woman allegedly tried to kill her 11-week-old niece by giving her breast milk laced with pain medicine.

WANE reports that Sarai Rodriguez-Miranda, 19, was charged Monday with attempted murder, though she is not yet in police custody. Rodriguez-Miranda was reportedly angry that her brother, his girlfriend, and their infant child were staying at her mother’s house, leading her to devise the deadly plot.

Police began investigating in January, after the suspect’s grandmother reportedly uncovered texts Rodriguez-Miranda sent on a phone they shared, according to WLKY.

An affidavit acquired by The News-Sentinel revealed that the text conversation addressed how much acetaminophen, caffeine, and aspirin was needed to kill the infant, and noted that 4,000 mg is lethal to an adult.

Rodriguez-Miranda’s mother recalled seeing a picture of a mortar and pestle with a large amount of white powder on her daughter’s phone.

“I’m gonna crush up some of these pills since she decided they can stay longer and kill their baby,” the suspect reportedly wrote to her boyfriend.

“I put the stuff in a made bottle in the fridge. Yeah I thought it was funny that I don’t have an ounce of guilt.”

The grandmother located two bottles in the refrigerator—one contained breast milk that appeared darker than normal and showed possible residue at the bottom. She then took the infant to the emergency room, and the baby showed no signs of being poisoned, according to WANE.

The child’s mother told officers that she hadn’t fed her daughter with either bottle. The 19-year-old’s grandmother allowed police to search the home and supplied them with the pill bottles and mortar and pestle she suspected may have been used to taint the breast milk.

The grandmother also told police that Rodriguez-Miranda left the state with her boyfriend, stating that she didn’t want her brother’s family living with them, The News-Sentinel reported. Authorities believe she fled to Michigan to avoid arrest.

WANE reports that a forensic toxicologist determined that there were nine Excedrin tablets in the one baby bottle—more than enough to kill the infant, who weighed less than 10 pounds at the time. The bottle also contained lethal amounts of caffeine and aspirin, according to the affidavit.

An arrest warrant has been issued for the teen.

[Featured Image: Allen County Sheriff’s Department]