Maybe people confuse Copernicus with the advocate of related theories Giordano Bruno, who was killed in 1600 for his beliefs and advocacy (though not only for his beliefs about astronomy).

https://en.wikipedia.org/wiki/Giordano_Bruno

People may also confuse Bruno with Galileo Galilei, who was punished by the Inquisition for his defense of Copernican theory, but not executed.