The Latest on the killings of three young Phoenix boys (all times local):

9:20 a.m.

Arizona child welfare officials had prior contacts with the family of three young boys found stabbed to death in their home.

The boys' 29-year-old mother is hospitalized with self-inflicted stab wounds. Police say the Phoenix woman is the primary suspect and will face charges.

The state Department of Child Safety says investigators couldn't locate the family in 2010 to check reports of a boy with a small abrasion on his forehead.

The department says it also investigated cases in 2011 and 2016 involving marijuana allegations in which it found no legal grounds to take the children into emergency care. One allegation was substantiated, and the other was not.

Director Greg McKay says the department takes seriously its responsibility to protect children but cannot predict the future, including "awful things" that people can do.

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1:15 a.m.

The Phoenix mother had been transported to the hospital covered in blood with stab wounds to her neck and abdomen when police officers searching her house opened a closet to a grim discovery.

Inside, officers found the bodies of her three young sons.

Police discovered the dead boys — ages 2 months old and 5 and 8 years old — in a closet full of miscellaneous items. Phoenix police Sgt. Trent Crump said the youngest boy's body was in a suitcase.

Crump said the children appeared to have been stabbed to death and "parts of their bodies were dismembered."

The 29-year-old mother is in the hospital in critical condition with self-inflicted stab wounds. Police say she is the primary suspect and will face charges.