A Customs and Border Protection officer stands at the Paso del Norte border crossing bridge at Ciudad Juarez, Mexico, on Monday. (Jose Luis Gonzalez/Reuters)

U.S. Customs and Border Protection was aware of the inflammatory Facebook page where alleged Border Patrol agents posted racist, sexist and violent images — and the agency has investigated posts from the group on at least one occasion, an official said.

CBP’s Office of Professional Responsibility, akin to an internal affairs division, received content from the group once called “I’m 10-15” in 2016, said the official, who spoke on the condition of anonymity to discuss a personnel investigation. The office carried out an inquiry and took disciplinary action, but the official did not say how many employees were involved or what sort of discipline was dispensed.

Even though some in the agency have known about the Facebook group for as many as three years, CBP officials do not conduct regular monitoring of private pages, the official said, adding that it would potentially interfere with members’ First Amendment and privacy rights. Instead, CBP responds when it’s presented with reports of wrongdoing.

Officials have said they weren’t aware of the recent posts to “I’m 10-15” — which has reportedly been renamed America First — and Kevin McAleenan, acting secretary of Homeland Security, pledged “an immediate investigation” after the website ProPublica published an investigation revealing a bevy of offensive posts on the page.

“Any employee found to have compromised the public’s trust in our law enforcement mission will be held accountable,” McAleenan said on Twitter.

The fact that CBP officials knew the group existed — first reported by Politico — enraged lawmakers and migrant advocates.

“What is profoundly disturbing is that the Border Patrol agents and leadership who posted these heinous things have power over migrants — including vulnerable women and children,” said Rep. Veronica Escobar (D-Tex.) on Twitter. “This is truly a broken agency in desperate need of complete reform.”

Rep. Alexandria Ocasio-Cortez (D-N.Y.), who was the target of sexually violent posts on the Facebook page, said on Thursday that CBP officials told members of Congress the agency didn’t know about the group.

“Looks like CBP lied,” she said in a tweet.

On Friday, another Facebook group of apparent CBP personnel surfaced, revealing even more posts containing insensitive, derogatory and lewd content. The page, called “the Real CBP Nation,” was first reported by CNN and has about 1,000 members. The outlet did not review the group but did obtain images of it and images posted there, including jokes about migrant deaths and more memes attacking Ocasio-Cortez.

A Facebook spokesperson told The Washington Post that the company had removed several posts to that group because they violated policies on bullying and harassment, cruel and insensitive content, and sexual exploitation of adults. Facebook did not ban the group.

In a Tuesday letter to Facebook chief executive Mark Zuckerberg, House Oversight Committee Chairman Elijah E. Cummings (D-Md.) said the posts to the “I’m 10-15” group also appeared to violate the social network’s “Community Standards.” Cummings requested copies of all the posts and comments made on the group, including deleted content.

The Facebook spokesperson said the company couldn’t comment on that group because it is cooperating with CBP’s internal investigation.

CBP has its own code of conduct that many of the disclosed posts would likely violate. The agency’s standards direct its employees to “sustain the trust and confidence of the public they serve.”

“The conduct of CBP employees,” the policy says, “must reflect . . . a standard of personal behavior that reflects positively upon, and will be a credit to, both CBP and its employees.”

Elizabeth Dwoskin contributed to this report.

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