The CEO of embattled UnitedHealth Group, Andrew Witty, who caused an uproar after defending the policies that led Luigi Mangione to allegedly murder the CEO of subsidy UnitedHealth Care, abruptly handed in his resignation on Tuesday.

The resignation caps off a tumultuous time for UnitedHealth Group since December, when the UnitedHealth Care CEO, Brian Thompson, was slain on a Manhattan street.

The murder sparked ongoing consumer backlash against the high cost of healthcare and denial of medical claims, which was exacerbated when an internal Zoom video conference was leaked that showed Mr. Witty defending the company’s practices in the immediate aftermath of Mr. Thompson’s death. 

In the video, which was originally obtained by an independent journalist, Ken Klippenstein, the former CEO defends the company’s policy of rejecting 32 percent of claims — twice the industry average.

“We guard against the pressures that exist for unsafe or unnecessary care to be delivered in a way that makes the whole system too complex and ultimately unsustainable,” he told employees in December of last year.

He also encouraged employees to “tune out” the public outrage, saying it does not “reflect reality.”

“The mission of this company is truly to make sure we help the system improve by helping the experience for individuals get better and better. There was no one who did more to try to advance that mission than Brian Thompson,” Mr. Witty said during the conference call that took place a day after the murder.

Mr. Witty attempted to quell the outrage from the public for his leaked comments in an op-ed published in the New York Times.

“We know the health system does not work as well as it should, and we understand people’s frustrations with it. No one would design a system like the one we have. And no one did. It’s a patchwork built over decades. Our mission is to help make it work better,” he said.

“Clearly, we are not there yet. We understand and share the desire to build a health care system that works better for everyone.”

Mr. Witty’s UnitedHealth Group has also faced other issues in 2024, such as when a cyber-attack crippled a hospital payment processor operated by Change HealthCare, affecting an estimated 100 million people.

Mr. Witty, who resigned due to unspecified “personal reasons,” was immediately replaced by the board chairman, Stephen J. Hemsley.

“We are grateful for Andrew’s stewardship of UnitedHealth Group, especially during some of the most challenging times any company has ever faced,” Mr. Hemsley, who previously served as CEO between 2006 and 2017, said in a statement announcing the change.

UnitedHealth shares dropped more than 15 percent after Tuesday’s announcement.