Wesley Farris, a high-ranking officer with El Paso’s Border Patrol Union, describes what it was like to separate migrant children from their parents in a new FRONTLINE documentary -- offering a rare public criticism of family separations from within Border Patrol's own ranks. “That was the most horrible thing I've ever done,” he tells FRONTLINE. “You can’t help but see your own kids.” Subscribe on YouTube: bit.ly/1BycsJW Farris was tasked with separating families under a 2017 "zero tolerance" pilot program in El Paso, Texas. It was, he says, a tough order: “I mean, none of us were happy about it,” he tells FRONTLINE. “But everybody around me was just doing exactly what… We were all told to do this.” Experts say the tactic causes lasting trauma. In the above excerpt from the FRONTLINE documentary "Targeting El Paso," Farris tells FRONTLINE about the effects he witnessed on a child during the last family separation he conducted. “It was a young boy. I think he was about two. The world was upside down to that kid,” Farris says. “So when the contractor tried to take him away, he reached for me and he climbed up on me again, and he was holding on to me. So that that one got me a little bit.” After that, Farris says he drew the line: “I said at that one, ‘I’m not doing this anymore. I won’t do it. I went back to the supervisor and I told him, ‘Don’t assign me to do that anymore.’” Farris didn’t complain up the chain, but told FRONTLINE he wanted to. For more on Farris's story -- and how the El Paso area became a testing ground for some of the Trump administration's most controversial immigration policies -- stream "Targeting El Paso" in full starting Tues., Jan. 7: to.pbs.org/2Fnq6Io Instagram: www.instagram.com/frontlinepbs Twitter: twitter.com/frontlinepbs Facebook: www.facebook.com/frontline FRONTLINE is streaming more than 200 documentaries online, for free, here: to.pbs.org/hxRvQP Funding for FRONTLINE is provided through the support of PBS viewers and by the Corporation for Public Broadcasting. Major funding for FRONTLINE is provided by the John D. and Catherine T. MacArthur Foundation and the Ford Foundation. Additional funding is provided by the Abrams Foundation, the Park Foundation, The John and Helen Glessner Family Trust, the Heising-Simons Foundation, and the FRONTLINE Journalism Fund with major support from Jon and Jo Ann Hagler on behalf of the Jon L. Hagler Foundation. Past support for FRONTLINE’s YouTube channel provided by The John S. and James L. Knight Foundation.