When President Trump and Joe Biden faced tough questions about immigration policies during their final debate, it spurred discussion of the Trump administration’s “zero-tolerance” policy that resulted in the separation of an estimated 4,000 children from their parents at the southern U.S. border.

News reports had recently surfaced that the federal government still couldn’t find the parents of 545 children separated during a pilot program that predates the zero-tolerance policy put into effect in May 2018.

During the sharp exchange, the candidates fired allegations at each other about which administration started separating families and who “built the cages.” Here are the facts:

When asked about the 545 parents separated from their children, Trump said the “children are brought here by coyotes [human smugglers] and lots of bad people, cartels — and they are brought here and they used to use them to get into our country.” Is he correct?

No. Federal court filings show that their adoptive or biological parents brought the children in question to the U.S. Children who are brought over without their parents, by smugglers, are often classified as “unaccompanied minors” and are not included in the group the moderator asked about.

“They did it. We changed the policy and they built the cages. We did not build the cages.” Did the Obama administration build the cages?

The Obama administration did build the cages Trump alluded to. The facility Trump mentioned was built with chain-link fencing by the Obama administration in 2014 in a warehouse in Nogales, Ariz. The makeshift shelter was built in response to an exodus of unaccompanied immigrant children from Central America. But those children did not arrive with their parents; they were unaccompanied. The shelter was not being used as part of a child separation policy, and U.S. border agents did not separate those children from their parents.

Did the Obama administration separate families at the southern U.S. border?

Yes, U.S. border officials did separate children from their parents on occasion, but it was not as widespread or systematic as it became under the Trump administration, particularly during its “zero-tolerance” policy, which was meant to deter migrants from seeking refuge in the U.S.

What was the “zero-tolerance” policy?

The policy directed U.S. prosecutors to criminally charge everyone who crossed the border without inspection. Parents were then separated from their children when they were taken into custody. Many of these parents were deported to their countries of origin — mostly to El Salvador, Guatemala and Honduras. Trump scrapped the policy in June 2018 after a massive public outcry. But separations still occurred under other policies (see below).

Who is looking for the 545 parents separated from their children? Trump said the U.S. government is “working on it” and “trying very hard” to find the parents. Is that true?

No. Although a federal court compelled the administration to provide contact information for the parents, U.S. officials are not doing the searching. Instead, the court appointed a steering committee of nongovernment organizations, including the American Civil Liberties Union and Justice In Motion, because the U.S. government refused to conduct a search. The Trump administration kept poor records, which exacerbated the situation, according to a Department of Homeland Security’s inspector general report.

Where are the children of the more than 500 parents who are being sought? Biden said the “kids are alone” with “nowhere to go.” Trump said they are in clean facilities and well taken care of. Who’s right?

Neither. The children are no longer in detention centers; they are with extended family members in the U.S. or with foster families.

Did family separations at the southern border stop after Trump did away with the zero-tolerance policy?

No, between 1,100 and 1,200 children were separated after the policy was scrapped in 2018.

Federal officials still separated children from their parents for different reasons, such as doubt about the familial relationship between a child and their parent or if the accompanying adult had any sort of criminal record — including minor violations and arrests — in the U.S. or their country of origin.

Immigration rights activists and lawyers argued in court in a 2019 lawsuit that the separations were unlawful and accused the administration of exploiting loopholes to continue to separate families.

In court filings, the ACLU said the administration used allegations of criminality or even mere suspicion to justify family separations.