The family 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, David Dao's daughter said Thursday.

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

Dao, 69, remains hospitalized with a broken nose, damaged sinuses, and other injuries that included the loss of two teeth when he was pulled from his seat and dragged off a flight Sunday, lawyer Thomas Demetrio said. He said Dao "probably" will file a lawsuit. A hearing on preserving evidence from the scene is set for Monday in Chicago.

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.

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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.

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"I think you will see an effect on sales from those who are disgusted by the gruesome action," said Eric Schiffer, CEO of Reputation Management Consultants. "It’s catastrophic for a brand’s trust."