PHOENIX — Almost one of every 12 child-abuse complaints reported to CPS since January was not investigated.

Top officials blame the failure on decisions by agency workers that, based on the information from a phone call, the reports were not important enough to follow through on.

Department of Economic Security Director Clarence Carter said Thursday that his top investigator just learned in the last two weeks that there has been an unofficial policy at Child Protective Services of marking certain complaints “not investigated” even before any further inquiry was done.

He said the process started as a way to prioritize cases to deal with limited resources, but had accelerated to the point where nearly half those 6,000 cases designated “NI” since 2009 occurred this year, despite state law that there be at least some investigation of every complaint that meets certain criteria.

The practice would still be going on except for its being accidentally discovered two weeks ago by Gregory McKay, head of the agency’s newly created Office of Child Welfare Investigations. Carter insisted he knew nothing of the practice and said he was shocked by the findings.

“The idea that there are 6,000 cases that we don’t know whether or not children are safe, that’s cause for grave alarm,” he said.

Of the nearly 3,000 cases shunted aside since Jan. 1, a review conducted to this point found 23 complaints of actual criminal conduct, 10 of which were so concerning a caseworker was immediately sent out.

Among the ignored complaints reviewed thus far, McKay said, it turns out there have been 125 subsequent reports of abuse involving the same people. But he said caseworkers assigned to investigate those new complaints never knew of the earlier calls because of the way CPS keeps records.

Carter denied any involvement in instituting or approving the practice, but he sidestepped questions of who in the agency first authorized the use of the “NI” designation to ignore cases.

“What I would ask is that you would allow me to complete my full review in order to be able to answer those questions,” Carter said.

But Gov. Jan Brewer took the issue out of his hands, ordering the state Department of Public Safety to determine “precisely how and why this inexcusable failure occurred.”

Rep. Debbie McCune Davis, who serves on a special CPS oversight committee, questioned whether even that will provide real answers on “who to hold accountable.” She pointed out DPS, like DES, ultimately reports to the governor.

Brewer said she named Carter to head DES in 2011 because she was confident of his ability to run the wide-ranging agency. Beyond CPS, it is responsible for everything from child support and food stamps to unemployment benefits.

But the governor said she is reserving judgment on what happens from here until she has a final report.

“Then we can decide who is responsible,” she said.

Brewer said she was upset so many cases had gone uninvestigated, particularly as state law requires follow-up of some sort for every complaint. “This is a nightmare, and we’re not going to tolerate it,” the governor said, calling what happened “an inexcusable failure.”

Dana Naimark, president of the Children’s Action Alliance advocacy group, called the findings “incredibly disturbing.” But she also said that, in some ways, they are not surprising.

“This is another piece of evidence showing us how overwhelmed the system is and that it cannot function,” Naimark said. She said there are 10,000 cases listed as “inactive,” meaning there has been no follow-up for at least 60 days, and that it takes “months and months” to close cases that should be addressed much quicker.

Carter said the screening process that shunted cases aside has stopped and investigators are now going back through the rest of those 6,000 cases to see whether further action is appropriate.

But Naimark questioned how it will be possible to do that and respond to new complaints given that the agency already is so far behind.

“I can’t tell you exactly at this moment how this is going to happen,” Carter said.

The latest disclosure comes on top of complaints that CPS does a poor job even when caseworkers do go out and investigate. There have been multiple cases where staffers go out, decide not to remove a child from a home but a youngster later ends up dead, including three in a one-month period earlier this year.

As McKay describes it, calls come in to the CPS “hotline,” where staffers decide, first, whether it is even an allegation of abuse and, second, whether there is evidence a crime has been committed. All of those cases were then entered into the computer to be sent to the appropriate field office.

But McKay said a special team was reviewing the cases and deciding some that showed no immediate evidence of a crime should be marked “NI.” That removed them from the computer queue even before a field supervisor got a look.

McKay said he learned about the process after a police officer asked one of his investigators about the status of a case in which an older sibling was accused of molesting a younger one. His own inquiry into that case, made nine months after the initial report, found that “NI” designation.

A second similar incident McKay discovered led his team to go back through older records, which Carter said showed many cases that should have been assigned a lower level of intervention were branded “NI” and dropped instead.

McKay did not provide specifics. But he said, to date, his investigators have found no case in which a child has died because of the failure to follow up.

Carter said the use of that “NI” designation, which started in 2009, was done “relatively sparingly” until the last six or seven months.

Carter is asking for another 350 workers for this coming budget year. But Brewer said blaming the practice on lack of funding is “totally unacceptable.”

“It’s the law” that every complaint which meets certain criteria be investigated, she said. “And the law must be followed.”