A U.S. Army veteran who served two tours in Afghanistan has been deported to Mexico, US Immigration and Customs Enforcement said.

The deportation follows an earlier decision by U.S. authorities to deny Miguel Perez’s citizenship application because of a felony drug conviction, despite his service and the PTSD he says it caused.

Perez, 39, was escorted across the U.S.-Mexico border from Texas and handed over to Mexican authorities Friday, ICE said in a statement.

Perez, his family and supporters, who include Sen. Tammy Duckworth of Illinois, had argued that his wartime service to the country had earned him the right to stay in the United States and to receive mental health treatment for the PTSD and substance abuse.

Perez was born in Mexico and legally 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 told CNN earlier. He has two children born in the United States. His parents and one sister are now naturalized American citizens, and another sister is an American citizen by birth.

It’s a complicated case. Perez has said that what he saw and experienced in Afghanistan sent his life off the rails, leading to heavy drinking, a drug addiction and ultimately to his felony conviction.

In 2010, he was convicted in Cook County, Illinois, on charges related to delivering more than 2 pounds of cocaine to an undercover officer. He was sentenced to 15 years and his green card was revoked. He had served half his sentence when ICE began deportation proceedings. He had been in the agency’s custody since 2016.

Perez has said he was surprised to be in ICE detention and mistakenly believed that enlisting in the Army would automatically give him U.S. citizenship, according to his lawyer, Chris Bergin. His retroactive application for citizenship was denied earlier this month. While there are provisions for expediting troops’ naturalization process, a main requirement is that the applicant demonstrate “good moral character,” and the drug conviction was enough to sway the decision against his application, Bergin said.