An Arizona man faces a federal murder charge for allegedly holding his 6-year-old son’s face under hot water for several minutes to cast out a “demon.”

Pablo Martinez, 31, told police he had noticed in the past week that his son was possessed by a demon. While he was bathing his son and his other child Thursday on the Pascua Yaqui Indian Reservation near Tucson, Martinez told investigators he saw something evil in his son and knew he had to get rid of the demon.

The boy became unnaturally angry, Martinez told investigators, so he allegedly held his son’s head under the bathtub faucet for five to 10 minutes so the hot water would run into his mouth. The water was casting out the demon, Martinez told investigators.

Michael Areinoff, a public defender representing Martinez, declined to comment on the allegations.

Belief in demonic possession is not a fringe idea. Slightly more than half of Americans polled in a YouGov survey in 2013 said they believed in it, and 46 percent reported that they believed exorcisms could drive out demons. Demand for Catholic exorcisms has been growing in recent years, the Atlantic reported.

The 6-year-old boy, his adoptive mother, Romelia Martinez, and his biological mother are members of the Pascua Yaqui tribe, according to a criminal complaint. Pablo Martinez, who is believed to be in his 30s, is not a member. It was not clear Tuesday if he and Romelia Martinez were married.

The Pascua Yaqui tribe said in a statement that “as a close-knit community, this loss weighs heavy on all of our hearts.” They said the tribe was offering counseling and support services to its members, and they asked people to respect the privacy of the boy’s family.

While Martinez held his son’s face under the faucet, his other child left the bathroom crying, according to the complaint. Romelia Martinez heard gurgling coming from the bathroom, unlocked the door and saw Pablo Martinez holding the boy down under the faucet, the complaint says.

Romelia Martinez screamed at him to stop several times, she told investigators, but Pablo Martinez told her that “he had to do it.” She allegedly tried to call a pastor, but he did not answer the phone, so she called 911. Pablo Martinez then attempted CPR on the boy and poured cold water on him, the complaint says.

Police arrived at the home to find the Martinezes standing outside. When officers asked what had happened, Romelia Martinez allegedly said something along the lines of, “He can tell you,” referring to Pablo. Pablo Martinez told police they would not understand what had happened because they were not of the right mind-set or belief, the complaint says.

As police kept questioning him, Pablo Martinez allegedly turned his back to them, raised his hands in the air and said something to the effect of “I did it.” He allegedly told police there was a demon inside his son and that he “needed to save him.” Romelia Martinez also told police the boy had been acting demonic, the complaint says.

Police found the boy, who was naked and did not seem to be breathing, propped up on a pillow on top of a bed, the complaint says. He was brought to Banner University Medical Center in Tucson and was pronounced dead about 5:30 p.m. The boy had burns on 15 percent of his body, including on his forearms, elbows and head, according to the complaint.

The boy was a first-grade student at Lynn/Urquides Elementary School in Tucson, the school confirmed.

Pablo Martinez was detained after his first court appearance Friday and held in the custody of the U.S. Marshals Service, court records show.

In addition to the Pascua Yaqui Police Department, the FBI also responded to the scene. The FBI has investigative responsibilities for major crimes committed on about 200 Native American reservations across the country.

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