Dao -- a 69-year-old physician from Kentucky who was involuntarily bumped to make room for United crewmembers en route to another job -- allegedly acted "violently” and yelled, "I am not leaving this flight that I paid money for. I don't care if I get arrested,” when the responding officers tried to persuade him to exit the aircraft, according to the incident report, which was released in response to a public records request.
In a supplemental incident report, also obtained Monday by ABC News, another officer said that Dao's "combative" arm-swinging made the officers lose their grip on him, causing him to fall and hit his mouth on the armrest across from him. Dao's attorney, Thomas Demetrio, has since said the doctor suffered a broken nose, injury to his sinuses, concussion, and lost two front teeth.
According to a hospitalization report filed by Chicago police and obtained by ABC-owned station WLS, Dao and his wife had initially "expressed interest" in taking United up on their offer to re-accommodate passengers on a later flight in exchange for an $800 voucher, but later "declined after learning they were not guaranteed a flight later this evening."
The couple was later informed they'd been selected by the computer to surrender their seats. When they refused to deplane, a United supervisor called aviation security officials.
Eventually, a plainclothes officer pulled Dao from his seat and removed him "by dragging him due to the fact that the subject would not stand up," according to the supplemental report.
According to the plainclothes officer's personnel file, obtained by ABC News, he had just returned from a five-day disciplinary suspension for "insubordination" in late March. (Several months prior, he had been ordered to block a gate with his vehicle, but instead allowed the vehicle to pass through, according to the incident description in the file. He was suspended because he "failed to obey a direct order," the document states.)
After the Dao incident, the plainclothes officer, along with three others, was placed on paid administrative leave. The officers' union had no comment on the incident.
The incident, which was videotaped by other passengers at the O'Hare International Airport in Chicago, sparked a national outcry and three of the involved aviation officers were subsequently placed on leave, according to the aviation department.
United CEO Oscar Munoz apologized for the incident and has vowed that the company will conduct a "thorough review” of the "truly horrific event.”
The Aviation Department also instructed its employees to review the organization's "use of force" policy, which indicates that security personnel should use force only when "reasonably necessary to defend a human life, effect an arrest or control a person," and that the force used "shall only be that which is necessary to overcome the resistance being offered by an offender and to effect lawful objectives."
Demetrio, who told ABC News on Monday that he and Dao are "getting ready" to take legal action, called the officers' allegations of aggression by Dao "utter nonsense."
"Consider the source," he said in a statement.
Demetrio is also representing an American Airlines passenger who is at the center of another viral video posted to Facebook on Friday. That footage shows an intense confrontation between a flight attendant and at least two passengers after a woman tried to bring her double-wide stroller on board a plane.
ABC News' Andy Fies, Rebecca Jarvis, Becky Perlow, and Jeffrey Cook; WLS' Christine Tessel; and The Associated Press contributed to this report.