ATLANTA – In 1907, Italian educator Maria Montessori created a revolutionary teaching method that encourages independence and promotes the idea that children can teach themselves with little help from adults.

Nearly 100 years later, Montessori’s great-great-granddaughter was slain after getting mixed up in drugs and running away from home.

Hanna Denise Montessori, 15, of suburban Atlanta, died of a head wound in January after being found unconscious in the street in Santa Ana, Calif. It was not until last week that her identity was established.

No arrests have been made in the slaying, and details about how she was killed have not been disclosed.

“It’s ironic that my great-grandmother was Maria Montessori,” Hanna’s father, Derek Montessori, said from his home in Windham, Maine.

The Montessori method, used in thousands of schools around the world, from preschool to high school, encourages independent learning. Maria Montessori believed that children learn not so much from their teachers as from their surroundings, their peers and themselves. Children usually get about three hours a day of uninterrupted time when they can choose their own activities.

Hanna attended a Montessori school for a few months in Texas when she was 3. Her great-aunt, Renilde Montessori, is affiliated with Association Montessori Internationale in the Netherlands.

Derek Montessori said his daughter used to be a good student who never got into trouble.

“She wanted to be a nurse,” Montessori said. “She enjoyed life. She was your average all-American little girl.”

But after her parents divorced in 1999, the 11-year-old girl became bitter and rebellious, her father said.

She began “doing the opposite of what everyone wanted her to do,” Montessori said. Then came the alcohol and drugs. She began using marijuana and “I imagine whatever else she could get her hands on,” he said.

Montessori said he brought her to live with him in Maine, but she was out of control. He sent her back to her mother in Georgia.

Hanna later became a ward of the state because of allegations that she was abused at her mother’s suburban Atlanta home, and she ran away from group homes twice last year.

Her mother, Cheryl Montagu, would not comment on the abuse allegations. “I’m going through a horrible grieving process because I loved my daughter very much,” she said.

Derek Montessori said he does not believe the abuse charges; he said Hanna just wanted to free herself from her parents’ supervision.

A missing-persons report was filed after she ran away. A month before her death, she was arrested in Los Angeles for loitering, and was fingerprinted. Her father said her fingerprints should have led authorities to identify her as a runaway.

But for some reason that did not happen. He suggested that may have cost her her life.