The origins of the posters are unknown, but they reference clues found at the murder scene of UnitedHealthcare CEO Brian Thompson.

Luigi Mangione, the man charged in the killing of UnitedHealthcare chief executive Brian Thompson, did not have coverage from the health insurer, the company said Friday.

Andrew Witty called the U.S. healthcare system “a patchwork,” but readers slammed UnitedHealth for contributing to its inequities, leaving the op-ed’s intent overshadowed by fury.