A US Border Patrol agent on horseback tries to stop a Haitian migrant from entering an encampment on the banks of the Rio Grande near the Acuna Del Rio International Bridge in Del Rio, Texas on September 19, 2021.
CNN  — 

The horse patrol incident in Del Rio, Texas, that drew swift condemnation from senior Biden administration officials will not be investigated by the Department of Homeland Security’s inspector general, the department announced Tuesday.

US Customs and Border Protection had referred the incident – where Border Patrol agents on horseback aggressively confronted migrants – to the watchdog, according to the Department of Homeland Security. Instead, CBP’s Office of Professional Responsibility is now investigating the incident, the department said, adding that the office has reviewed videos and photographs and interviewed witnesses, employees and CBP leadership.

The incident garnered national attention in September when photos surfaced of agents on horseback swinging long reins near migrants who had crossed the border near Del Rio, Texas – where around 15,000 migrants had amassed under the Del Rio international bridge.

Homeland Security Secretary Alejandro Mayorkas said he was “horrified” by the incident and had previously pledged he was committed to completing the investigation in “days, not weeks.” But nearly two months later, the probe continues.

“Once completed, the results of the investigation will be provided to CBP management to determine whether disciplinary action is appropriate and, if so, the specific discipline to be imposed. At that time, the employees will be afforded due process, including an opportunity to respond, and any corrective actions will comport with applicable laws and regulations,” DHS said in a statement Tuesday.

“The disciplinary process, which is separate from the fact-finding investigation, is subject to certain timelines established in CBP’s labor-management agreement with the employees’ union of the United States Border Patrol,” the statement added.

During a Senate hearing Tuesday, Republican Sen. Mike Lee of Utah pressed Mayorkas on his response to the Del Rio incident at the time, asking why he did not defend the Border Patrol. Mayorkas pushed back, saying that an independent investigation will determine the facts and eventually, the outcome.

The agents involved in the incident remain on administrative duty, according to DHS spokeswoman Marsha Espinosa. Horse patrol units continue to be deployed based on operational assessments, but are not deployed in the city of Del Rio, she added.

CBP’s Office of Professional Responsibility is charged with investigating alleged misconduct of CBP employees. The office may share initial findings with the US Attorney’s Office to alert federal prosecutors of the case and “ensure that administrative actions do not inadvertently compromise any potential criminal investigation,” DHS said. The Office of Professional Responsibility might wait to interview people until the US attorney decides whether or not to pursue the case.