An Arizona man has been charged with first-degree murder after the authorities said he killed his 6-year-old son by forcing hot running water into his mouth for several minutes as part of an attempted exorcism.

The man, Pablo Martinez, 31, told responding police officers that the child had a demon inside of him and needed to be saved, according to the criminal complaint.

He was arrested on Thursday at the family’s home on the Pascua Yaqui Tribe Reservation, located about 10 miles southwest of downtown Tucson . He was detained after a hearing on Tuesday morning, prosecutors said.

Mr. Martinez told federal officials that he had noticed a “demon” inside of his son during the previous week, according to court documents. He said when he was giving his son a bath, along with another child, his son started to have “an unnatural fit of rage,” the documents said. Mr. Martinez said he saw something evil and had to cast it out by holding his son’s head under the bathtub faucet.