A California woman under investigation in the killing of two children was visited by county child welfare workers several times over the course of a year to check on complaints of neglect, an official said.

Police in the Northern California city of Redding, where the bodies of a boy and a girl were found inside a storage unit, said Wednesday the children died somewhere else and that police in Salinas, where the children had lived until recently, will lead the investigation.

Redding police said detectives determined during the investigation the children's death occurred outside Shasta County and gave no other details. It said an autopsy was performed Wednesday but the results have not been announced.

Child welfare workers repeatedly visited the Salinas home of the 39-year-old woman now under investigation in the deaths of two children to check on complaints of neglect, said Elliot Robinson, head of the Monterey County Department of Social Services.

None of the five children living in the apartment were removed from woman's care because there was no evidence they were at risk, Robinson said.

There were four complaints between September 2014 and August about general neglect, a category that includes poor supervision, improper feeding, lice infestation and dirty household conditions, Robinson said, adding that none of the complaints alleged physical abuse.

"General neglect calls rarely will result in the removal of the child," he said. "More often than not it's about poverty."

Two of the children at the home belonged to the woman, and the other three had been placed in her care by their incarcerated father after their mother died, Robinson said.

The AP typically does not identify abuse victims; it is not naming the woman and a teenage suspect because their relationship to the children is unclear.

On Friday, a 9-year-old girl suffering from neglect and abuse was found near a house in Quincy, where the woman had recently moved. Later, police investigators found two children, ages 3 and 6, dead in a storage locker in Redding.

The woman and the 17-year-old male were arrested and charged with child abuse, torture and mayhem. Each remained jailed on $1 million bail. They have been named as suspects in the deaths, but they have not been charged.

The investigation began Friday with the discovery of the starving 9-year-old girl who was taken to a hospital.

Plumas County Sheriff Greg Hagwood told the Sacramento Bee that some officials were so shaken by the abuse endured by the girl that they might have to take time off to recover.

"When you see what has been done to a beautiful little 9-year-old girl ." the sheriff said before stopping to regain his composure. "Anyone not affected needs to get some help."

Plumas County authorities got a call from someone in Monterey County asking about the two younger children. Detectives questioned the woman and teenager again, and learned of the storage locker, the sheriff said.

The woman and teen appeared in court Tuesday, but they did not enter pleas. Their arraignments were set for Jan. 7. Their attorneys declined to comment.

Social services officials were reviewing the agency's handling of the four neglect complaints. "We're looking at the case to see if there's anything we should have done differently that could have prevented this tragedy," Robinson told the San Francisco Chronicle.