David Dao

He reportedly told officials that he is a doctor and could not leave the flight because he had patients to see in Louisville early Monday morning, according to the Courier-Journal.

His license permits him to practice internal medicine at an outpatient facility once a week, according to documents obtained by PEOPLE.

Dao was arrested in as part of an undercover operation. Two years later, Dao was convicted on six felony counts of obtaining drugs by fraud and deceit and in , he was sentenced to five years probation.

Dao was also convicted for writing prescriptions and checks to a male patient in exchange for sexual favors. In response, the state medical licensing board issued a suspension that was lifted in Last year, the medical board imposed restrictions on his right to practice.

He can only practice internal medicine in an outpatient facility one day a week. While I deeply regret this situation arose, I also emphatically stand behind all of you.

You saw us at a bad moment. He doesn't remember anything after he bumped his head on the low ceiling.

The first few months were "horrible," he said. He suffered a concussion, lacerations to his mouth and nose, and several of his teeth were knocked out, he said.

He was put on suicide watch by hospital staff and later spent months learning to walk again, he said. Dao relied on his faith during his recovery, he said, adding that he made a promise to God that if he got better, he would devote his time to charity work.

Since then, he has helped residents in Texas displaced by Hurricane Harvey and traveled to Vietnam and Cambodia to help install solar power in villages with no electricity, he said.

Even in the Far East, people knew his story, he said. Dao still struggles with issues sleeping and with his concentration and balance, he said.

While he'd run more than 20 marathons before the incident, now he can only do about 3 miles -- with at least one of them by walking, he added.

While United's initial statement labeled Dao as "belligerent," the airline later apologized, vowing to conduct a "thorough review" of the "truly horrific event.

We can't do that. When asked whether United should have done anything differently, Dao said the airline employees could have explained their reasoning for booting him from the flight "nicely" and "reasonably.

Still, the retired doctor said his ordeal actually was "positive" because the airline was willing to take a hard look at its policies and change them.

Weeks after the incident, the airline offered Dao a settlement that his attorney at the time, Thomas A. Otros tres pasajeros acordaron abandonar el vuelo, y Dao fue seleccionado para ser el cuarto.

El presidente de los EE. Justo antes de las p. Fue un liderazgo deficiente". Tengo que llegar a casa Soy doctor. No necesitaba saltar a ese nivel ".

Tres de los pasajeros seleccionados, una pareja y una mujer que se cree que era la esposa de Dao, aceptaron irse.