ALBUQUERQUE, N.M. » A New Mexico teenager has pleaded guilty in the shooting deaths of his parents and three young siblings.

Nehemiah Griego appeared at a brief court hearing today in children’s court. He pleaded guilty to two counts of second-degree murder in the deaths of his parents and three counts of child abuse resulting in death in the slayings of his three younger siblings in a rural area south of Albuquerque.

Griego was 15 when he opened fire at his family’s home in January 2013. Authorities say after the killings, Griego reloaded his parents’ two semi-automatic rifles, put them in the family van and planned to gun down Wal-Mart shoppers.

A hearing will be held in January to decide whether Griego will be sentenced as a juvenile or an adult.