ALBUQUERQUE, N.M. — The New Mexico Attorney General’s Office on Thursday appealed the sentencing of a man who pleaded guilty to killing his parents and three siblings when he was teenager.

Attorney General Hector Balderas filed a 42-page brief with the state Court of Appeals, asking judges to consider Nehemiah Griego’s premeditation of the murders, his mental health issues and his violent tendencies as justification for sending the case back to court for more hearings.

Griego, now 19, was 15 when he opened fire at his family’s home south of Albuquerque in January 2013.

In March, a Children’s Court judge sentenced Griego as a juvenile instead of an adult. Griego will remain in state custody until he turns 21 in March 2018.

Treating Griego as an adult would’ve given him the possibility of up to 120 years in prison.

Griego has been undergoing therapy since May 2014 at a state facility for adolescents where his teachers, psychiatrists and others say he has made significant progress after being diagnosed with schizoaffective disorder, post-traumatic stress disorder and some learning disabilities.

According to authorities, Griego first killed his mother as she slept and then his 9-year-old brother and two sisters, ages 5 and 2.

Griego waited in a bathroom and ambushed his father, a gang member turned pastor, after he returned home, authorities said.

A message left for the public defender’s office that represented Griego seeking for comment on the appeal wasn’t immediately returned Thursday afternoon.