Lakeland, Florida -- A Lakeland mother believes bullying drove her 12-year-old daughter to take her own life on Monday.

Polk County detectives are investigating Rebecca Ann Sedwick's death, but have not called it a suicide at this time.

They say Rebeccaleft her home on Arizona Avenue in Lakeland around 6:45 a.m. Monday to walk to a bus stop for school. Shenever got on board. It was later discovered she had left home without her school books.

When Rebecca did not return after school, her mother reported her missing.Her body was found shortly before 2:30 a.m. Tuesday at a shuttered cement plant on North Eastside Drive in Lakeland. Detectives say the investigation is ongoing.

Rebecca was a 7th grader at Lawton Chiles Middle Academy, and had recently transferred from Crystal Lake Middle School.

Lawton Chiles principal Sharon Neuman tells 10 News that Rebecca had never complained of having any trouble at school or of being bullied.

Rebecca's mother, however, says her daughter was bullied by a group of girls at her old school last year.

"She would come home every day and say she's not worth anything, that she was ugly, stupid," recalls Tricia Norman.

Norman says a bullying complaint was filed with the school district back in January and her daughter.

"Crystal Lake should have disciplined these girls bullying her, taken it it more seriously. They blew it off," says Norman.

Rebecca was pulled out of Crystal Lake Middle School a month later and home schooled until she began the new school year at Lawton Chiles.

But online bullying started up again on websites such as Instagram and Ask.fm. Rebecca had been on Facebook, but her mom says they deleted it.

Lawton Chiles Principal Sharon Neuman is sending a letter home to parents letting them know of Rebecca's death. Crisis counselors will be on hand at the school for students and faculty today and tomorrow.

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