(CNN) Miguel Perez Jr. discovered that two tours of duty in Afghanistan with the US Army and an accompanying case of PTSD are no shield from US immigration laws.

Because of a 2010 drug conviction, Perez, 39, sits in an US Immigration and Customs Enforcement detention center in Kenosha, Wisconsin, awaiting possible deportation to Mexico -- a country he left more than three decades ago. Many are rallying around Perez's case as an example of what they say is the US's desperately broken immigration policy.

There are serious factors working against Perez: He was convicted on a felony drug charge and discharged from the Army for drug use; military service is no guarantee of citizenship; and he never applied for citizenship, despite being eligible to apply in 1994.

He said he fears deportation would do more than separate him from his family in the United States, including his two children born here. He thinks it could kill him.

The substance-abuse and mental-health counseling he desperately needs would not be readily available in Mexico, he said. He also predicts that drug cartels would recruit him because of his combat experience and murder him if he didn't cooperate.

So he started a hunger strike Wednesday, not long after his latest setback in federal court.

"If they are sentencing me to a certain death, and I am going to die, then why die in a place that I have not considered my home in a long time?" he asked.

"There is a saying that goes, 'I'd rather die like a man than live like a coward.' In Mexico, I will have to live in fear, like a coward. No. I'd rather die right here, like a man fighting against something that makes no sense -- this thing of deporting veterans does not make sense even if they try to justify with the law."

Though US Citizenship and Immigration Services has provisions for expediting troops' naturalization process, a chief requirement is that the applicant must demonstrate "good moral character."

Veterans not immune from deportation

Perez is not the first veteran of the US military to face deportation.

In 2016, CNN interviewed several veterans in Tijuana, Mexico, after they were deported from the United States. Those veterans said they considered their homes to be the United States, not Mexico.

Like some of those veterans, Perez mistakenly believed enlisting in the US military would automatically make him a US citizen, said his lawyer, Chris Bergin.

In a statement, ICE said the agency "respects the service and sacrifice of those in military service, and is very deliberate in its review of cases involving US military veterans. Any action taken by ICE that may result in the removal of an alien with military service must be authorized by the senior leadership in a field office, following an evaluation by the office of chief counsel."

"ICE exercises prosecutorial discretion, when appropriate, on a case-by-case basis for members of the armed forces who have served our country. ICE specifically identifies service in the US military as a positive factor that is considered when deciding whether or not prosecutorial discretion should be exercised."

Between fiscal years 2002 and 2015, US Citizenship and Immigration Services naturalized more than 109,000 service members.

Enlisted before 9/11

Miguel Perez Sr. holds a photo of his son, Miguel Perez Jr., on April 4 in Chicago.

Perez was born in Mexico and came to the United States at age 8 when his father, Miguel Perez Sr., a semi-pro soccer player, moved the family to Chicago because of a job offer, Perez said.

His father, mother and his 47-year-old sister were born in Mexico but are now naturalized American citizens, he said. His 27-year-old sister and his daughter, 21, and son, 11, are American citizens because they were all born in the United States, he said. His daughter's mother, who he divorced, and his son's mother, to whom he was not married, are both citizens, Perez said.

Perez said he played soccer as a kid, and when he was 12 his team won a state championship. He did well in math and science and started college after finishing high school.

But Perez said he left college a few credits short of an associate's degree and enlisted in the Army in 2001, several months before 9/11.

Perez said he served in Afghanistan from October 2002-April 2003 and May 2003-October 2003, his lawyer said. Bergin added that Perez left the Army in 2004 with a general discharge after he was caught smoking marijuana on base.

Post-Army problems

Miguel Perez Jr. served in the US Army but did not become a US citizen.

After leaving the Army, Perez's life went off the tracks. He attributed these problems to post-traumatic stress disorder, which was not immediately diagnosed.

"I saw many horrible things, things I can only, until this day, speak about with a mental health specialist and even then after I say them, the nightmares start up again," he said. "They are things that happened to me personally, that happened to others, and to Afghans themselves -- 12-, 11-year-old kids split in half by 50-caliber bullets at our hands.

"These are things that you never forget and sometimes when you try to forget, they come back at night."

He said he became addicted to drugs and drank heavily.

"After the second tour, there was more alcohol and that was also when I tried some drugs," he said. "But the addiction really started after I got back to Chicago, when I got back home, because I did not feel very sociable."

Perez also had legal problems, including a conviction in 1998 for possessing a small amount of marijuana, Bergin said.

In 2007 he was charged with misdemeanor battery but the charge was dropped, Bergin said. At that time, he had already been diagnosed with PTSD at a veterans hospital, Bergin said.

He was later arrested on a felony cocaine charge.

Cocaine conviction

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Perez was convicted in February 2010 in Cook County, Illinois, on charges related to his delivery more than 2 pounds of cocaine to an undercover officer. He was sentenced to 15 years on a charge of manufacture or delivery, or possession with intent to manufacture or deliver a controlled substance, ICE spokesperson Nicole Alberico said.

With that conviction, he lost his green card, Perez said.

But prison had its benefits.

"It was in prison that I was finally able to get the treatment I needed for my PTSD," he said. "They had a lot of substance abuse programs, and now is when I finally feel like the person I used to be. I won't say a new person, but like when I was younger."

He also finished his associate's degree.

Perez had served half his sentence when ICE began deportation proceedings, with a judge ordering his removal in March 2017. Perez said he was surprised to be sent to an ICE detention facility because he thought he already had citizenship.

"Although he was a vet, he never applied for US citizenship for many years he was eligible," a senior immigration official told CNN. "He became a permanent resident in 1989. This means he could have applied for citizenship as early as 1994."

Esperanza Perez outside court in 2016.

Perez said he also started talking more to his children. On Saturday night he spoke with his son and they talked about Sunday's Super Bowl and sports.

Perez appealed the deportation order, but a three-judge panel of the 7th US Circuit Court of Appeals rejected his plea last week.

He could be deported this month.

Final appeals

Perez's lawyer, Bergin, filed an appeal to the full panel of the 7th US Circuit Court of Appeals, and will ask for a stay of deportation while the appeals process plays out.

Bergin said the requests for a stay are based on two arguments: A medical finding says Perez needs immediate attention for PTSD, and an application for retroactive citizenship -- based on the date of his enlistment in the military -- is still being reviewed.

Finally, supporters have petitioned Illinois Gov. Bruce Rauner for a pardon. A spokeswoman for the governor said the petition is under review.

Fear of drug cartels

Perez said the hunger strike is more than a symbolic gesture.

"I am fasting because if my deportation is final and they send me back to Mexico, I will be separated from my kids, from my family, my community, my home -- they are throwing me out, sentencing me to death," he said.

The drug cartels in Mexico are a real threat, he said.

"When I was in prison, I was already getting offers, people who would say to me that if I was deported (the cartels) would send word back and all would be OK," he said. "They would offer me the opportunity to make a lot of money and a lot of other things, but that was just a way to say, 'You belong to us when you get back here.'"

He said he's paid the price for his drug case, and is angrier by the day about his deportation.

"I went through the system and I accepted all of the consequences that came with declaring myself guilty of a crime, the way it should be," Perez said. "And now they want to deport me with nothing, without thinking to themselves that I sacrificed my life fighting for this country.

"It's very sad and now I'm starting to get angry because those same people that authorize, that support the deportation of veterans, those are the same people that the rest of us fought to protect."