UnitedHealth Group CEO Andrew Witty, in his first public remarks since the killing of executive Brian Thompson last week, said the U.S. healthcare system is “flawed” and called for its reform on Friday. “We know the health system does not work as well as it should, and we understand people’s frustrations with it,” Witty wrote in a New York Times opinion published Friday. The system is “a patchwork built over decades,” Witty said.