The CEO of United Airlines has issued a stronger apology about a passenger who was dragged off a United Express flight, calling the Sunday afternoon confrontation "truly horrific."

Oscar Munoz said in a statement issued Tuesday that he continues to be disturbed by the events that unfolded at Chicago O'Hare, adding that, "No one should ever be mistreated this way."

Munoz was widely criticized for two statements Monday about the altercation, in which he described the 69-year-old man taken off the plane as "disruptive and belligerent."

On Tuesday afternoon, however, the CEO changed his tune slightly, vowing to "fix what's broken so this never happens again."

The full statement, which was also posted on Twitter, reads:

The truly horrific event that occurred on this flight has elicited many responses from all of us: outrage, anger, disappointment. I share all of those sentiments, and one above all: my deepest apologies for what happened. Like you, I continue to be disturbed by what happened on this flight and I deeply apologize to the customer forcibly removed and to all the customers aboard. No one should ever be mistreated this way.

I want you to know that we take full responsibility and we will work to make it right.

It’s never too late to do the right thing. I have committed to our customers and our employees that we are going to fix what’s broken so this never happens again. This will include a thorough review of crew movement, our policies for incentivizing volunteers in these situations, how we handle oversold situations and an examination of how we partner with airport authorities and local law enforcement.

We’ll communicate the results of our review by April 30th.

The statement was signed by Munoz.

Meanwhile, The Associated Press reported the man dragged off the flight by airport police in Chicago is a Kentucky-based physician who was convicted more than a decade ago of felony charges involving his prescribing of drugs.

Still, there's no indication his past influenced how he was treated or that the airline or police were aware of his background. And it's unlikely that officials would have known anything about him other than basic identifying information such as his name and address, if that.

A person with knowledge of the Sunday evening flight who was not authorized to publicly release the information told The AP the passenger was David Dao, 69, of Elizabethtown, Ky.

According to a statement released Tuesday Dao is undergoing treatment in a Chicago hospital for his injuries.

“The family of Dr. Dao wants the world to know that they are very appreciative of the outpouring of prayers, concern and support they have received. Currently, they are focused only on Dr. Dao’s medical care and treatment,” said Chicago attorney Stephen L. Golan of Golan Christie Taglia, who along with Chicago aviation attorney Thomas A. Demetrio of Corboy & Demetrio, represents the Dao family.

While screaming can be heard on the videos, nowhere is Dao seen attacking the security officers. In fact, he appears relatively passive both when he was dragged down the aisle of the jet and when he is seen standing in the aisle later saying quietly, "I want to go home, I want to go home."

The Associated Press contributed to this report.