A 16-year-old Tennessee boy faces a first-degree murder charge in the fatal stabbing of his principal.

The district attorney's office in Tennessee's Shelby County said Tuesday that Eduardo Marmolejo of Memphis has been indicted in the death of 49-year-old Suzette York.

York was the principal of Memphis Junior Academy, a private high school affiliated with the Seventh Day Adventist church. Police said Marmolejo planned York's death for months before stabbing her repeatedly in a classroom on the third day of school last August.

Marmolejo has been held without bond since his transfer from juvenile court to adult court.

His lawyer, Leslie Ballin, said Marmolejo is unable to clearly understand the legal process and is not mentally able to stand trial as an adult.