PHOENIX, ARIZONA -- WARNING: Details in this story may be disturbing to some

An Arizona woman accused of killing her two children with a meat cleaver became the subject of a child services investigation two months ago and at one point had been taken to a psychiatric hospital, child welfare officials said Tuesday.

The Arizona Department of Child Safety said in a statement that the agency was alerted on March 2 about a case of neglect in suburban Phoenix involving Yui Inoue, 40, after she and her 7-year-old son Kai went missing from the family's apartment in Tempe.

Police found them behind a convenience store. Inoue was taken to a psychiatric hospital and the boy was returned to his father. Officials did not say how long she was hospitalized or provide details on her release.

An Arizona DCS investigator later interviewed the family but did not report finding any visible signs of child abuse or neglect involving the boy or his 9-year-old sister Mia. Both children said they felt safe with their parents, according to the statement.

Citing a lack of evidence, the agency opted not to remove them from the home. The investigation was still considered open when the children were found dead Saturday.

"As the community is struggling to grasp the tragic death of two innocent siblings, the Department is caring for staff who have also been impacted," the agency said. "Our prayers go out to the family and all who knew Mia and Kai."

Police had been called to the family's apartment earlier Saturday about a domestic dispute involving a husband and wife. At the time, officers said there was no apparent reason to call child welfare authorities.

It's not clear if the officers were aware of the ongoing investigation. Tempe police did not immediately respond to a request seeking comment.

Later that morning, Inoue went to a Tempe police station and said "she was hearing voices telling her to kill her children," according to charging documents. Officers went to the apartment and found the mutilated bodies of the children under a blanket and boxes.

Her husband, who has not been identified, told police the couple had filed for divorce in April and had argued the night before over money she wanted so she could move to Japan.

He said she threatened to stab him so he left just after midnight and slept in his car in a parking lot. He said he did not think she would harm their children.

Inoue is facing two counts of first-degree murder. She is currently being held on a US$2 million cash bond.

It was unclear Tuesday if a court-appointed attorney had been assigned to her case.

Students, teachers and others in the Tempe school district where the children were students were devastated by the deaths.

Counselors are being made available at Kyrene del Cielo Elementary School throughout the week.

"Moments like this remind us that life is precious and too often fleeting," Laura Toenjes, Kyrene School District superintendent, said in a statement. "Please hold your children and loved ones close."