KVOA Tucson reports that when emergency crews arrived at the home Martinez told police that "his son was demonic and had a demon inside of him".
Martinez admitted to pouring hot water down the child's throat and his wife Romelia Martinez, the child's adopted mother, told police that the child "had been acting demonic".
Romelia Martinez later told police that "she heard a gurgling sound coming from the bathroom" after her husband offered to bathe the boy and their other child.
She said she saw her husband holding down the 6-year-old under the hot tap. After she reportedly told her husband to stop, her husband told her that "he had to do it", according to court documents.
Those court documents state that the child's father told police that his son had an "unnatural fit of rage" and that he "noticed that the hot water was casting out the demon".
He told investigating officers that the child was under the water for over five minutes.
His wife called emergency services and the attempted CPR, but the child could not be revived.
The 6-year-old was a student at the local Lynn/Urquides Elementary School and school officials said he had special needs.
The school's principal released a statement after the tragic incident.
"It is with deep regret and sadness that I inform you of the death of one of our students. I want to let you know that Lynn Urquides Elementary administrative team has been working with TUSD Leadership and the Coordinator of TUSD Counselling to ensure that we provide every means of support and assistance to all the students, along with our staff.
"Our counsellors are available to help staff and any student who is struggling with death or other issues that may surface."
Martinez' attorney Michael Areinoff said that he had no immediate comment.
-Additional reporting, AP
