A daughter of the Kentucky physician at the center of a global uproar over his forced removal from a United Airlines flight said Thursday the family was "horrified, shocked and sickened" by the incident.

"What happened to my dad should never have happened to any human being, regardless of the circumstances," Crystal Pepper said at a news conference in Chicago.

David Dao, 69, remains hospitalized with a concussion, broken nose, damaged sinuses, and other injuries that included the loss of two teeth after he was pulled from his seat and dragged off a flight Sunday, lawyer Thomas Demetrio said. He said a lawsuit will be filed at some point.

"Dr. Dao, I believe to his great credit, has come to understand that he is the guy, the guy to stand up for all passengers going forward," Demetrio said. A hearing on preserving evidence from the scene is set for Monday in Chicago, he added.

Social media outrage rained down on the Chicago-based airline after videos emerged of Sunday night's violent confrontation on United Express Flight 3411 at Chicago's O'Hare Airport, drawing hundreds of millions of views around the world.

Demetrio called the video "rather disturbing." He said that neither United CEO Oscar Munoz nor other United officials have reached out to Dao. He also said he accepted Munoz's public apology — but said it was staged.

United spokesman Jonathan Guerin said all 70 seats on the Louisville-bound flight were filled when four passengers were told they had to give up their seats to accommodate crew members needed in Louisville the next day. The passengers were selected based on a combination of criteria spelled out in United’s contract of carriage, including frequent-flier status, fare type, check-in time and connecting flight implications, among others, according to United.

Three passengers went quietly. Dao balked, Chicago aviation authorities were called and a wild scramble ensued. The videos show three security officers speaking to Dao. One of the men grabs him, and he screams as he is yanked out of his seat and pulled down the aisle. Another video shows him bloodied and repeatedly saying, "I have to go home."

Three Chicago Aviation police officers have been placed on leave. The airline offered a string of sometimes awkward apologies and issued a refund for everyone on the flight. That was small change to United — a precipitous drop in stock price cost the company $250 million in value.

Eric Schiffer, CEO of Reputation Management Consultants, watched the news conference and said he agreed with much of what Demetrio had to say.

"Dao is now the protagonist for people refusing to be bashed in the teeth, horrified and bullied for United's failure to expect the unexpected," Schiffer said. "Dao's attorney is right that fliers deserve fairness, respect and dignity and not to get clobbered ... because airlines didn’t expect the unexpected

"I think his PR people said 'We're taking a beating here,'" he said. "I think he was told to get out there."

 Shortly after, United Airlines issued another apology to the man who was forcibly removed from a full flight, saying "we remain steadfast in our commitment to make this right."

In its statement, United insisted again that CEO Oscar Munoz and the airline called Dao numerous times to apologize. Munoz said Wednesday that he had left a message for Dao.

United spokeswoman Megan McCarthy told The Associated Press she saw call logs that showed Munoz and United's customer care team had reached out to Dao.