Reyna enlisted in the Army in August 2002. That fall, he and his wife enrolled in Pass Alternative High School in Kingman.
Reyna graduated within a couple of months and cared for their daughter, 4-year-old Savannah, while his wife earned her diploma.
"This is a tragic loss for the Reyna family, and the entire Tohono O'odham Nation mourns," said Vivian Juan-Saunders, chairwoman of the nation.
At the nation's San Xavier District on the southwest edge of Tucson, the flag was lowered to half staff in Reyna's honor over the tribal cemetery where dozens of O'odham veterans are buried.
"Something like this has an impact on a lot of people," said Preston, a former tribal government leader who confessed to mixed feelings of pride and sorrow.
"It made me feel sad that we had to lose a tribal member way over there on the other side of the ocean," Preston said.
Yet, "it's an honor that we still have some of our O'odham people in the service fighting for this country," he said.