The Michigan mother who shot her three daughters in the woods last Monday before killing herself in her boyfriend's driveway used a fake doctor's appointment to get her three daughters out of school and alone with her, investigators revealed.

Aubrianne Moore, 28, showed up at the children’s school in the middle of the day to pick up her daughters Alaina Rau, 2, Cassidy Rodery, 6, and Kyrie Rodery, 8, Kent County Sheriff’s Office detectives said. They added that her “doctor's note” that she gave to school administrators was fake.

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The mother's former social worker had warned about her behavior last September in a petition to the Newaygo County Probate Court. She wrote of the need to have Moore committed to a mental hospital.

“Aubrianne is keeping her kids home from school because the television told her there would be a school bus accident today,” the social worker wrote, as WYFF reported. “Aubrianne stays awake at night believing people will break into her home. Aubrianne is not eating believing food is being poisoned.”

The social worker also wrote: “I believe the individual has mental illness and as a result of that mental illness the individual can reasonably be expected within the near future to intentionally or unintentionally seriously physically injure self or others.”

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Investigators said Moore took her children to lunch before going to a wooded area behind a property that belonged to the children's great grandparents. She then took the children one by one into the woods and shot them with a bolt-action hunting rifle before driving back to her boyfriend's house and killing herself outside the vehicle, WOOD reported.

"I've been with the sheriff's department for 29 years," said Kent County Sheriff Michelle LaJoye-Young. "This is one of the hardest cases I've ever hear about. This is a very difficult case. Our investigators are feeling it. It's heartbreaking that something like this happened in our community."

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"Cassidy's teacher mentioned she was hard-working and friendly," Tri County Area Superintendent Allen Cumings wrote in a letter. "Kyrie's teacher also noted her love of reading and said she often volunteered to help others."

A GoFundMe page was set up by the girls' uncle Joseph Graham to cover funeral costs. It's raised over $9,700 as of Sunday evening.