"He remained loyal to the London-based Polish government-in-exile after the communist takeover of Poland and was arrested in 1947 by the secret police on charges of working for "foreign imperialism". Pilecki was executed after a show trial in 1948."

Incredibly sad, and probably typical of how communist regimes dealt with resistance heroes after the war. See František Fajtl [0] for instance.

[0] https://en.wikipedia.org/wiki/Franti%C5%A1ek_Fajtl#Persecuti...