Kristepher Benavidez, 25, and Monique Gaxiola, 30, were booked into Pima County jail. They are facing murder charges in the death of their toddler daughter.

Child Protective Services workers had prior contact with the mother of an 18-month-old twin girl who died Friday of injuries that police said were caused by repeated physical abuse.

Monique Gaxiola, 30, and Kristepher Benavidez, 25, are now facing first-degree murder charges in connection with the death of their daughter, Adyson Gallegos.

The pair were arrested last week on suspicion of child abuse but the charges were upgraded after the toddler died.

A CPS report said Adyson was taken to the University of Arizona Medical Center on Wednesday after she stopped breathing.

She was found to have blood coming from her ears, bite marks on both arms and right foot, scratches on her neck and bruising on her face and elsewhere on her body, according to the CPS report.

Tucson Fire Department personnel were called to a home in the 5200 block of South Newcastle Court, near South Midvale Park Road, on Wednesday on reports of a child not breathing..

While Fire Department personnel took Adyson to the hospital, police discovered her twin and a 7-year-old sister at a neighbor's home.

The older child appeared uninjured, but the twin girls had suffered “injuries that appeared nonaccidental,” Sgt. Chris Widmer, a Tucson police spokesman, said last week.

Detectives determined that the father had been physically abusing the twin sisters for an unknown period of time and the mother was aware of the abuse, Widmer said at the time of their arrests.

According to the CPS report, state child welfare workers had received a prior report alleging abuse or neglect of Adyson by Gaxiola. Information was not immediately available on that case.

The toddler's two sisters have been placed in foster care.