Border agents seen in controversial photos on horseback not yet questioned: Source

The U.S. Border Patrol agents at the center of a controversy stemming from their use of horses to block Haitian migrants from entering the U.S. have not yet been questioned more than a month after the incident took place, according to a law enforcement official.

Images of mounted patrol agents using their horses to push back migrants, mostly Haitian, stirred national controversy as an unprecedented number attempted to cross the Rio Grande into the small border town of Del Rio, Texas, in September. The Department of Homeland Security launched an internal investigation into the matter shortly after the images came out.

Homeland Security Secretary Alejandro Mayorkas promised a swift investigation into the horse patrol over a month ago, assuring lawmakers it would yield findings days later. As of publication, and despite multiple requests for comment from ABC News, the administration has not publicly announced any findings.

Preliminary findings from Customs and Border Protection's Office of Professional Responsibility have been handed over to the Justice Department to determine if criminal charges are warranted, according to two officials who were not authorized to speak publicly.

One law enforcement official said the internal investigation could not proceed, and the agents directly involved could not be interviewed, until the U.S. attorney makes a determination.

Referrals to U.S. attorneys are common in federal law enforcement personnel matters and do not necessarily indicate that criminal charges are being considered. The U.S. Attorney's Office for the Western District of Texas, which includes Del Rio, declined to comment.

"The investigation is ongoing," a DHS spokesperson said in a statement to ABC News. "The Department is committed to a thorough, independent, and objective process. We are also committed to transparency and will release the results of the investigation once it is complete."

Advocates for both migrants and the agents have been frustrated with the pace of the investigation so far.

Karen Tumlin, founder of the Justice Action Center, said a central concern is that the government has deported potential witnesses to federal police brutality in the time it has taken to conduct the investigation.

"[The delay] creates an 'out of sight, out of mind' issue," Tumlin said. "That was their intention."

Over the two-week period that migrants surged into Del Rio, border officials stopped about 29,000 of them, according to the Department of Homeland Security. More than 15,000 either returned to Mexico on their own or were sent to Haiti on rapid expulsion flights. About 1,800 were placed in U.S. Immigration and Customs Enforcement detention and some 13,000 were released on conditions to report back to authorities.

Jon Anfinsen, a Border Patrol agent and union leader, confirmed the mounted patrol agents remain on administrative duties, which he said has impacted the unit's ability to perform their normal patrol work.

Congressman John Katko, Republican ranking member of the House Homeland Security Committee, said Mayorkas and President Joe Biden were too quick to judge the agents involved.

“They wasted no time in vilifying these agents before hearing their side of the story,” Katko said in a statement to ABC News. “It’s shameful that this Administration continues to denigrate and demoralize law enforcement without a full picture of the facts.”

The horse patrol appears to be back up and running in Del Rio, Texas, despite silence from the Biden administration on the results of the internal probe. Use of the horse patrol was stopped at the Del Rio International Bridge in the days following the confrontations.

White House press secretary Jen Psaki was unequivocal in announcing the end to the use of Border Patrol horses in Del Rio last month, calling it a "policy change." DHS officials clarified at the time that it was only a temporary suspension.

"The secretary also conveyed to civil rights leaders earlier this morning that we would no longer be using horses in Del Rio," Psaki said at a Sept. 23 White House press briefing. "So that is something -- a policy change that has been made in response."

A CBP official who was not authorized to discuss the matter publicly disputed Psaki's characterization.

"They pulled all horse patrol agents for maybe a day or so to process," the official said referring to the administrative duties agents are required to perform when migrants flood the area. "Then it was right back to normal sector-wide, with the exception of a couple more agents under scrutiny."

CBP Assistant Commissioner Luis Miranda said the horse patrol remains suspended in the city of Del Rio. But it continues to be used across some 55,000 square miles of the surrounding Del Rio Border Patrol Sector.

A photo posted to the USBP Del Rio Sector's Facebook page on Oct. 7 shows Border Patrol agents on horseback detaining a group of men huddled on the ground.