She is charged with making a terroristic threat, but her lawyer says she was simply venting to fellow teachers. Prosecutors say the art instructor was in a teachers' lounge at the school when she threatened to go on a machine-gun rampage to settle scores.
Prosecutors say she threatened it would be "Columbine all over again," referring to the 1999 high school shooting in Colorado.
Milo is under orders to stay away from the school.
Her attorney insists she's innocent and that she doesn't even own any weapons.
She faces up to seven years in jail if convicted.
Officials said Milo has had issues in the past. She was removed from the classroom last May and sent to the "rubber room," where New York City teachers accused of wrongdoing or incompetence were sent until a hearing could be held. The Bloomberg administration and the teachers union agreed to do away with that policy this year.
Teachers are now reassigned to administrative duties or non-class work while they await their cases are pending.
Milo resumed teaching last September.
She has been with the school and the Department of Education since 2001.
Officials said she will face disciplinary action when legal proceedings are completed.