Griego told the detective that his brother woke up but did not believe him that their mother was dead, so he showed his mother's bloody face to his brother and then shot him, according to the statement.
The teen is accused of then shooting his two young sisters after they began crying in their room, and retrieving a military-style semi-automatic rifle from his parents' closet and waiting in a downstairs bathroom for his father to come home. The statement said he shot his father multiple times after he passed the bathroom doorway.
Greg Griego was a pastor who had once served at Calvary, one of Albuquerque's largest Christian churches. He also was well-known throughout the law enforcement community for his work as a voluntary chaplain.
A records check by the Children, Youth and Families Department indicated no problems with the Griego family and that Nehemiah Griego had never been in trouble with the law.
Sheriff's Deputy Aaron Williamson confirmed there was no history of any emergency calls to the home in the recent past.
Associated Press writer Paul Davenport in Phoenix contributed to this report.