A new report from the Office of the Inspector General of the Department of Health and Human Services finds that an unknown number of children — possibly “thousands” — were separated from parents at the US-Mexico border before June 2018 but hadn’t been included in official government tallies of separated families.

The Trump administration’s practice of separating families who crossed into the US without papers (by prosecuting parents for illegal entry into the US and sending them into criminal custody, while children were reclassified as “unaccompanied” minors) became a nationwide scandal in the late spring of 2018, leading to a Trump administration executive order ending the policy and a federal court order requiring the administration to reunite the separated parents and children in its care.

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But separated children who had already been released from the government’s custody — usually by being placed with a sponsor — weren’t identified and reunited as part of that lawsuit. In the new report, HHS is admitting that there could be thousands of such children, and that they’ll never have any way of knowing how many for sure.

The new report doesn’t — and can’t — identify where separated children released from custody were placed. But despite fears (among politicians and the public) of widespread “loss” or trafficking of immigrant children, the available evidence suggests most separated children (like children who arrive unaccompanied) were placed with close relatives in the US.

But the point of the report is the government’s admission that it will never be able to know for sure how many children were separated and exactly what happened to them. Even the estimate of “thousands” is offered without much explanation, as an estimate of officials at the Office of Refugee Resettlement and HHS’ office for preparedness and response.

Because of the federal government’s failure to keep records about which children in its care had been separated from their parents, the public will never know the full scope of the Trump administration’s use of family separation against border crossers in Trump’s first year and a half in office.

Thousands of children weren’t included in the reunification order because they’d already been released

The federal government has never offered an official tally of how many families have been separated by immigration authorities. It couldn’t produce one if it tried.

When families are separated at the border, the children are classified as “unaccompanied alien children” (the label put on children who come to the US without a parent or guardian) and sent into the custody of Health and Human Services, which is responsible for placing them with a sponsor.

Until summer 2018, there was no official way to record the difference between a child who’d come without a parent and a child who’d been separated from one in the files that were sent from DHS to HHS.

HHS’s job isn’t to hold children until a parent can be identified, but to place them with a suitable sponsor — a parent, other relative, family friend, or (if needed) unrelated adult — as soon as safely possible. And if a child turns 18, or decides to return to their home country, they’re no longer HHS’s responsibility.

Family separation was an occasional practice going back as far as late 2016, but it ramped up hugely as the Trump administration instituted a “zero tolerance” policy of prosecuting as many adults as possible for illegal entry into the US, and separating parents from their children to be sent into criminal custody.

A Customs and Border Protection official told Reuters in June 2018 that from October 2016 to February 2018, 1,800 families were separated by DHS. Of those families, 281 were separated as part of a “pilot program” along the El Paso sector of the border from June to November 2017.

According to the new inspector general report, staff at HHS started noticing in summer 2017 that more of the children being sent to them by DHS seemed to have been separated from parents. (Informal HHS tracking, according to this report, showed that in late 2016, only 0.3 percent of children sent from DHS appeared to have been separated from their parents; by August 2017, 3.6 percent were identified as possibly separated from family.)

In spring of 2018, that pilot was expanded across the US-Mexico border, and separations rapidly spiked. From October 2017 to April 20, 2018, an HHS official told the New York Times, about 3.46 families were separated a day; over 12 days in May of 2018, DHS told Congress, that rate spiked to 42.8 separations a day.

On June 26, 2018, Judge Dana Sabraw ordered the federal government not only to stop separating families (something the Trump administration had promised to do as a matter of course the week before) but to reunify them. To do that, it had to identify the number of separated children who were in the government’s care at that time. That number — about 2,737 as of December — is what’s typically taken as the number of separated families.

But Sabraw’s order only applied to children who were in HHS custody on June 26. It didn’t apply to children who had already been released.

The inspector general’s report is estimating that that is what happened to “thousands” of children: They were separated from their parents when they entered the US, but by the time HHS started identifying separated children, they were no longer under HHS’s care.

Generally, children are released to close relatives, but we don’t know how many of the separated children were released to nonrelatives

HHS has strict rules about who it’s supposed to allow to sponsor an immigrant child. The first priority is a parent or legal guardian; the second priority is a close relative; the third priority is a distant relative or family friend, and only failing that, an unrelated adult.

In general, this means that the overwhelming majority of children whom HHS places with sponsors are sent to parents or close relatives. (A 2016 government report found that about 60 percent of immigrant children who came unaccompanied from Guatemala, Honduras, or El Salvador were placed with a parent living in the US.) There have been some high-profile cases of insufficient vetting of would-be sponsors, but the Trump administration has reacted to that by substantially tightening vetting, to the point of keeping kids in custody a lot longer than they were under the Obama administration.

Because HHS doesn’t actually know how many of the children it released from custody before June 26, 2018, were separated from parents at the border, it’s impossible to go back through those records and find out where the separated children went.

But by that same token, there’s no indication that HHS had different standards for the placement of separated children. So it’s reasonable to believe that most children were placed with relatives or family friends in the US (possibly even with parents who had been released from detention, or a parent already living here).

Overall, from fiscal year 2017 to the first eight months of fiscal year 2018, the share of kids placed with parents dropped from 49 percent to 41 percent, but the share placed with other close relatives rose from 41 percent to 47 percent. In other words, in both years, parents and close relatives made up about 90 percent of sponsors.

But it is possible that a disproportionate number of separated children were placed with unrelated sponsors as foster children — or released because they chose to be returned to their home country (perhaps to reunite with their parents). We don’t know. We’ll never know.