Jason Owens, the retiring chief, said he hopes future leaders remain impartial and keep politics out of the agency.

Narrator: From the Border Patrol Academy's six-month basic-training program. Daniel Harris: From day one, our goal is to make sure that they are prepared to handle anything that they may encounter ...

According to the union, the behavior seen in the video was a corrective technique taught at the Border Patrol's canine training academy: "The incident in question involves a canine handler ...