From: Rabbi Moshe Sofer
To: Rabbi Zelig
The Chasam Sofer rejects the Pnei Yehoshua's explanation that lashes for scheming witnesses who caused the defendant to be lashed derive from the independent prohibition of lo sa'aneh, raising three objections. He instead explains the Rambam's ruling through the Maggid Mishneh's principle that a lav haba michlal aseh combined with a kal vachomer permits deriving punishment min hadin, allowing lashes to be extended to the post-execution scenario even though ka'asher zamam velo ka'asher asah would otherwise exempt them.
Source: Shu"t Chasam Sofer CM §33