Parashas Masei · Passuk 35:21 · TT note 4
Chabad.org — English translation + Rashi
Torah Temimah points to Sanhedrin 45b (TT note on “מוֹת יוּמַת הַמַּכֶּה”).
E-Daf — Sanhedrin 45b · Sefaria
English: It was taught: From where [do we know] that if you cannot put him to death by the form of death prescribed for him, you put him to death by any form of death you can? From “the striker shall surely be put to death” — in any case.
Flexibility of execution method when the prescribed form is unavailable.
The court may use any available means of execution if the specific method written for that crime cannot be carried out.