Images of drug cartel shootouts from five or six years ago show a dead body in front of a wall with hundreds of bullet holes. That’s not the case anymore, Daniel Torres, a U.S. Marine Corps veteran, said.

“Nowadays, you see a dead body with two shots to the chest and one in the groin. That’s how military members shoot. So you have to ask yourself, who’s teaching them to shoot or who is doing the shooting,” Torres told the filmmakers of “Ready For War,” a Showtime film premiering at 9 p.m. Friday about U.S. military veterans who get deported to Mexico.

Miguel Perez, a U.S. Army veteran who was raised in Chicago and later deported to Mexico — he was a legal resident when he served in the military — told the filmmakers he was approached by drug cartels when he was at a U.S. prison for nonviolent drug crimes.

“Certain people were like, look, if you get deported, you have nothing to be worried about,” he said. “In other words, it’s ‘We’re claiming you.’”

Miguel Perez in "Ready for War." Jeffrey Peterman / Courtesy of SHOWTIME

Thousands of foreign-born U.S. veterans have been deported to Mexico and other countries following the passage of immigration laws in 1996 under the administration of President Bill Clinton. They expanded the types of conduct that can lead to deportation and eliminated immigration judges' discretionary authority to consider factors such as long residence, rehabilitation, family ties and military service.

Drug cartels, gangs and other terror organizations have sought to exploit such changes to recruit deported veterans, according to Perez, civil rights organizations and others interviewed in the film.

“In Mexico, we have to deal with the cartels, but what about the guys that are deported to the Middle East and they gotta deal with ISIS and all this other terror organizations,” Perez told NBC News. “This is a worldwide problem when it comes to deported veterans.”

Most deported veterans are sent to Mexico, where they were originally from, where they face serious death threats from gangs and drug cartels looking to recruit them because of their military training, according to the American Civil Liberties Union.

While Perez didn't succumb to the cartel threats, other veterans weren’t as lucky.

A still from "Ready for War." Jeffrey Peterman / Courtesy of SHOWTIME

An army veteran nicknamed “El Vet” became part of the Juárez cartel in Mexico after being deported nine years ago. He said the cartel threatened to kill his family if he didn’t join. Feeling stranded and lonely in a country he didn’t grow up in, “El Vet” said he went to “the other side,” and started training cartel soldiers.

“Every day of his life down there, he was submitted to the fact that he probably wasn't going to be living for very much longer,” filmmaker Andrew Renzi, who followed deported veterans, including some who were with the drug cartels, to make “Ready For War,” told NBC. “It's just the world that he chose to live in. Not even necessarily chose, but the world he was caught in. It's truly a war down there."

Mike Vigil, a former DEA chief responsible for all operations outside the continental United States, who also worked as an undercover agent in Mexico for 31 years, told filmmakers that between 60 and 70 percent of all drugs smuggled into the U.S. go through the Juárez-El Paso corridor, meaning that veterans deported to Mexico are in the hands of a “deadly enemy” and "have basically created a national security threat.”

The Department of Homeland Security did not respond to NBC News' request for comment.

Mexico and the U.S. have a long history of fighting the cartels but homicides, which are mostly drug related, hit a new high of almost 36,000 in 2018 and are occurring at about 90 slayings a day, according to the Council on Foreign Relations. Since Mexico began waging anti-drug campaigns in 2006 with U.S. help, over 300,000 homicides have occurred.

'A portion of our society we’re supposed to take care of’

Perez was diagnosed with post-traumatic stress disorder after serving two tours in Afghanistan in the early 2000s. Upon his return home to Chicago, he struggled to adjust to civilian life as he was recovering from a traumatic brain injury. Perez was sentenced to 15 years in prison after facing drug crime convictions in 2010.

After doing time in prison, immigration authorities detained Perez, who was a legal permanent resident, and put him up for deportation. Chris Bergin, Perez's lawyer, argued that cartels in Mexico would likely recruit him if he was deported.

And yet, Immigration and Customs Enforcement, or ICE, denied his application for U.S. citizenship and deported him last year to the Mexican state of Tamaulipas — which has a “Level 4: Do Not Travel” advisory “due to crime and kidnapping,” according to the U.S. Department of State.

Miguel Perez poses as he holds a photo of his son Miguel Perez Jr., on April 4, 2017 in Chicago. Joshua Lott / AFP - Getty Images file

Supporters of deported veterans’ rights such as San Diego County Supervisor Nathan Fletcher and Democratic Sen. Tammy Duckworth of Illinois have said that former soldiers who face difficulties adjusting to civilian life, including substance abuse and other mental health or physical issues, should receive treatment instead of deportation orders.

ICE has not been consistent or effective in the way it tracks, reviews and decides cases involving veterans facing deportation since at least 2013, according to a recent report from the U.S. Government Accountability Office.

The report also states that the number of citizenship applications from military members received by U.S. Citizenship and Immigration Services declined sharply between 2017 and 2018, resulting in a decreased number of applications approved. The Department of Defense attributed the decline to several policy changes the agency implemented in 2017 to reduce the number of noncitizens who join the military, the accountability office said.

"This was a change from the previous practice of certification of honorable service after 'one day of service,'" Jessica R. Maxwell, a spokesperson at the Department of Defense, told NBC News in a statement, adding that military services "have great success attracting Legal Permanent Residents."

For Renzi, veterans are “a portion of our society that we're supposed to take care of when they come home.”

“That's not a Democrat or a Republican issue. That's a human issue,” he said. “We all lose our way at some point and it's unfortunate that certain people are treated differently than others who also lose their way.”

Perez ended up staying in Mexico for a year and a half after being deported. It wasn’t until a few months ago that he was able to get a pardon from Illinois Gov. J.B. Pritzker and be sworn in as a U.S. citizen.

"We weren't illegally deported," Perez said. "According to the legal system, everything was fine. But some of the laws and policies that are in place, really, are not moral because they destroy families that went to war for the country. My family dealt with the fear of me not coming, my health issues and dealing with PTSD."

“Slavery at one point was legal. That doesn't make it moral. That didn't make it right,” he added.

From deported veteran to a U.S. citizen

For the first time in his life, Hector Barajas-Varela wore his military uniform as a U.S. citizen on April 18, 2018, after waging a decade long fight to return to his home in California following his deportation in 2010.

"One of the biggest misconceptions is that soldiers who are immigrants have automatic citizenship when they join the military," Barajas-Varela said.

Just in 2016, the ACLU said that a third of the nation's 300,000 foreign-born veterans living in the U.S. had not processed their citizenship, one of the benefits they are promised when they enlist, because the government failed to naturalize noncitizen service members while serving due to "misinformation and administrative hurdles."

As Barajas-Varela fought his deportation for 10 years, he founded the Deported Veterans Support House in Tijuana, known as the “Bunker,” with the help of the U.S. Department of Veteran’s Affairs in San Diego.

His work has led to "a growing global network of deported veterans whose organization, power and voice will eventually stop the United States from deporting its own soldiers," according to the ACLU.

"We looked at Hector Barajas-Varela as somebody that had an injustice occur to him and then used that for good. He devoted his life to try to create positive change. He devoted his life to service, helping other veterans who were deported. And as a result of that change and service, he's rewarded," Renzi said.

Hector Barajas stand with his Mom Margarita Barajas during a press conference after a swear-in ceremony at the immigration office in Downtown San Diego, California on April 13, 2018. Barajas, a U.S. Army veteran, has been living in Tijuana Mexico and seeking U.S residency after being deported Eight years ago. He is the first known deported veteran to be naturalized as a U.S. citizen due to his honorable wartime service. He has been living in Mexico the last eight years. Sandy Huffaker / AFP - Getty Images

Barajas-Varela said that the many years of intense advocacy work has felt overwhelming at times. Now he's back in California with his teenage daughter, trying to focus on being a parent, find work and go to school. But his ultimate mission — ending veterans' deportations — remains, as he works with his many allies.

“We're now pushing for a change in legislation," Perez said, "because that’s the only thing that's going to help stop deportations.”

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