(CNN) -- A U.S. Border Patrol officer involved in the fatal shooting of a 15-year-old Mexican youth on the El Paso, Texas, border in June is back at work, a Border Patrol spokesman said Monday.
It was unclear how long the agent was on administrative leave before he returned to duty, but his work status was not known publicly until CNN inquired about the situation on Monday.
"I can tell you that after a traumatic incident, Border Patrol agents automatically have three days of administrative leave," Border Patrol spokesman Ramiro Cordero told CNN. Cordero said he was not certain exactly when the officer returned to duty but he thought it was about two weeks after the shooting.
Cordero would not identify the officer beyond saying he is a 7-year-veteran, and his name is being withheld by the department.
The officer received widespread condemnation from critics who questioned his use of deadly force against the teen, Sergio Adrian Hernandez Guereca, who authorities said had been throwing rocks at the agent when he was shot and killed on the fringes of the El Paso border with Ciudad Juarez, Mexico.
Guereca had a history of involvement with human smuggling and was on a list of repeat juvenile offenders, U.S. Customs and Border Protection spokesman Mark Qualia told CNN after the shooting.
"We have to make split second decisions and he was getting rocks thrown at him. Historically, this happens to us more than you'd think. There was one incident I can remember when a Border Patrol agent was killed by rocks, and then the guys shot him afterwards," Cordero said of the stress agent's face while "maintaining the integrity" of the border.
A multi-agency investigation involving the FBI and the U.S. Department of Justice was launched after the shooting. No charges have been filed against the officer.
"There are two aspects of [the investigation]. The assault of the [agent] is one part. The other part of it is the civil rights investigation. Both of those are ongoing," Andrea Simmons with the El Paso FBI field office told CNN. "We're trying to determine what happened. We're looking to see if any civil rights violations were made by the agent."
One of the loudest advocates for charges against the agent was Juarez Mayor Jose Reyes Ferriz. In a text message to CNN Monday, Reyes indicated he was unaware that the agent was back at work, but he did not comment further.