Unaccompanied minors from Mexico who end up in the hands of US border patrol agents are almost always denied safe haven, likely in violation of federal anti-human trafficking laws, according to a report published Tuesday by the Government Accountability Office.

Children under the age of eighteen who have no legal guardian in the United States are identified by the Department of Homeland Security as unaccompanied alien children (UAC), and must be, by statute, evaluated to ensure they aren’t deported if they face danger at home.

The GAO found, however, that Customs and Border Protection agents “made inconsistent screening decisions, had varying levels of awareness about how they were to assess certain screening criteria, and did not consistently document the rationales for their decisions.”

According to one case reviewed, a child was “emotionally distraught” and “unable to speak clearly,” and yet CBP determined that it was appropriate to send her back to Mexico.

“Because the agent did not document the reason for deciding that the child should be repatriated, it was unclear whether or how the agent took into account the child’s physical and mental state,” the GAO lamented, noting that a 2009 agency memorandum requires agents to consider a child’s emotion state as a factor in determining if they can make independent decisions about their immigration options.

In another case, “one child claimed fear of gangs and another claimed fear of violence in Mexico, and the interviewing agents decided to repatriate both [children].”

The Trafficking Victims Protection Reauthorization of 2008 requires that immigration enforcement agencies repatriate unaccompanied children only if it’s determined that they are “not victims of a severe form of trafficking” and “are not at risk of trafficking upon return.”

The law also requires agents to screen children to make sure they don’t have “a fear of returning due to a credible fear of persecution and are able to make an independent decision about returning.”

Should an unaccompanied child not pass any one of the screening measures, they are supposed to be transferred to the care of the Department of Health and Human Services.

Although CBP policy defines children under the age of 14 as unable to make independent decisions, the GAO reported that between 2009 and 2014, 93 percent of unaccompanied children under that age threshold were returned to Mexico “without documenting the basis for decisions.”

The report was released Tuesday—the same day as Homeland Security Secretary Jeh Johnson testified before a House Judiciary Committee oversight hearing.

During her questioning, Rep. Zoe Lofgren (D-Calif.) told the DHS chief that the GAO’s findings were “troubling,” adding that “we’re not really getting the kind of examination that the law envisioned.”

Rep. Lofgren went further, and criticized the department’s procedures when interviewing potential trafficking victims.

“You have a child who may be a victim of trafficking—they may have been a victim of sexual abuse—and yet their interrogation is conducted by a uniformed officer who may or may not speak their language, and in front of other children,” she told Secretary Johnson.

“You wouldn’t have a police agency in the entire United States that would interview a child abuse survivor in that fashion,” she added, urging Johnson to make sure children are in an “appropriate setting by skilled people.”

“It’s something that we will look at,” Johnson responded. The department had concurred with GAO’s findings and recommendations, and claimed it was working to “better assess a child’s ability to make decisions and the risk of trafficking if the child is returned.”