The Casualties at the Other End of the Remote-Controlled Kill

When she and Captain Larson had met in 2016, she said, he was already taking mushrooms once every few months, often with other pilots. He also took MDMA — known as ecstasy or molly — a few times a year. The drugs might have been illegal, but, he told her, they offered relief.

“He would just say he had a very stressful job and he needed it,” Ms. Larson said. “And you could tell. For weeks after, he was more relaxed, more focused, more loving. It seemed therapeutic.”

A growing number of combat veterans use the psychedelic drugs illicitly, amid mounting evidence that they are potent treatments for the psychological wounds of war. Both MDMA and psilocybin are expected to soon be approved for limited medical use by the Food and Drug Administration.

“It gave me a clarity and an honesty that allowed me to rewrite the narrative of my life,” according to a former Air Force officer who said he suffered from depression and moral injury after hundreds of Reaper missions; he asked not to be named in order to discuss the use of illegal drugs. “It led to some self-forgiveness. That was a huge first step.”

In Las Vegas, the civilian authorities were willing to forgive Captain Larson, but the Air Force charged him with a litany of crimes — drug possession and distribution, making false statements to Air Force investigators and a charge unique to the armed forces: conduct unbecoming of an officer. His squadron grounded him, forbade him to wear a flight suit and told him not to talk to fellow pilots. No one screened him for PTSD or other psychological injuries from his service, Ms. Larson said, adding, “I don’t think anyone realized it might be connected.”

As the prosecution plodded forward over two years, Captain Larson worked at the base gym and organized volunteer groups to do community service. He and his wife divorced. Struggling with his mental health, seeking productive ways to cope with the trauma, he read book after book on positive thinking and set up a special meditation room in his house, according to his girlfriend at the time, Becca Triano.

“I don’t know what he saw, what he dealt with,” she said. “What I did see toward the end was him really working hard to try to stay sane.”