Arizona authorities said a criminal complaint has been filed against a Phoenix man accused in the death of his niece, a 5-year-old Hawai'i girl.

Leonard Orta Jr., 47, was charged yesterday with first-degree murder, child abuse and concealing a body, the Arizona Republic reported.

Phoenix police arrested Orta last Wednesday after the body of Kaiya Kapahu was found in an apartment by her grandfather. Authorities said Orta was the girl's caregiver since last July and that she suffered from Rett syndrome, a neurological disorder that made her prone to seizures.

Police said Orta is accused of intentionally withholding his niece's medication and nutrition. Investigators say Orta told them that he stopped nourishing the child 10 days before her death and that she died more than a month ago.

He had been caring for the girl since August because the treatment she needed was not available in Hawai'i.

"This is one of the most disturbing cases that I have prosecuted," Maricopa County Attorney Andrew Thomas said yesterday.

Orta was charged with two forms of first-degree murder: one alleging premeditation, the other citing "felony murder" — that is, suggesting that the death occurred as a direct result of child abuse. A jury could choose between the two.