Was Mordechai mekayem the mitzvah aseh of מְכַשֵּׁפָה לֹא תְחַיֶּה based off the understanding of the Ramban here that it is a mitzvah Aseh to kill a sorcerer.
looking from the Kedushas levi Here it seems that Mordechai hanged Haman himself.
would this mean that Mordechai was mekayem MItzvah Aseh D'oraysa of killing a sorcerer?
additionally, from this it can seem that there are times that a conviction by beis din is not necessary.
(I wonder how many individuals throughout Jewish history have been mekayam this mitzvah...)