The 10-year-old boy choked by his mother on Jan. 30 died in a hospital Thursday morning, police officials said.
Charges against the mother, Jean Cataline, 49, have been upgraded from attempted murder to first-degree murder, Sgt. Chris Widmer, spokesman for the Tucson Police Department, said.
She is also charged with child abuse in the death of her son, John, who was a fourth-grader at Whitmore Elementary School in the Tucson Unified School District.
Cataline called 911 shortly after 10 a.m. Jan. 30, "stating she had just strangled her child" with an extension cord, according to court documents. "The caller would not respond to questions by the 911 call taker and seemed to be going into shock."
When officers arrived at the family's apartment, 2720 N. Swan Road at East Glenn Street, they found Cataline "on the floor in a bedroom ... still on her cellphone."
On the bed the officers saw an extension cord and the unconscious boy.
"The child had a purple face and officers began CPR," the documents stated. "While officers were with Jean, she kept uttering, 'What did I do? What did I do?' "
The boy was rushed to the hospital in critical condition.
The woman's other son, age 17, was placed in the custody of Child Protective Services.
The boys' father recently died, Widmer said.