I have 2 questions regarding the deRabbonon death sentence of kipa (confinement, barley diet, death):
(1) Death by Beis Din is a final kaporo for the person and is dependant upon his doing tshuva before being executed. Meaning, even after he does tshuva (which he must do), his death sentence is carried out.
Death by kipa is a deRabbonon din and that is why the death sentence is carried out by gromo (indirect, caused). Where is tshuva vis-a-vis this death sentence? Meaning, if the person is in confinement and is being fed barley etc, if he does full tshuva, is he released? Or is his sentence (i.e., he is kept in confinement until he dies) carried out regardless of his tshuva?
(2) Bror lo misa yofeh - select for the defendant the best death sentence. When there is a choice (in the gemoro's discussions) of which death sentence to use, the rule is to use the best ("nicest") death sentence. Presumably this means the death sentence that is faster, less painful, etc. Is this correct? If yes, then in my humble opinion, the Rabbonon death sentence of kipa is the longest and most painful (slow death by a sort of starvation). Why would the Rabbonon use such a long and painful death sentence, which seems to go against the Torah's guideline for selecting a death sentence. Aren't there other gromo (indirect) death sentences that are faster and less painful than kipa? I recall the gemoro discussing cases where a person is not guilty of murder (to get misas Beis Din, but yes get misa bidei Shomayim) if he kills someone in an indirect way. Why couldn't the Rabbonon use these indirect methods instead of kipa?
Thanks and kol tuv,
Chaim Mateh, Rechovot, Israel
1) Rashi 81b DH v'Heicha writes that the punishment of kipa is not derabanan but in fact is certainly Halacha l'Moshe miSinai. See also the Chidushei HaRan here who writes at length to prove that kipa is Halacha l'Moshe miSinai. However there is an opinion that kipa is a din drerabanan, as you write, Chaim. This is the opinion of Teshuvas Rivash #251.
I wish to suggest that the question concerning whether teshuva provides an exemption from kipa is dependant on this dispute between Rashi and the Ran on one side, and between the Rivash on the other side. Rashi and Ran maintain that kipa is essentially the same as every death by Beis Din. The only difference is that standard deaths by Beis Din are stated explicilty in the Torah, whilst kipa is Halacha l'Moshe miSinai (although it is hinted at in the Torah as the Gemara 81b states - see Rashi DH v'Heicha). Therefore it apears logical that according to Rashi and Ran, teshuva will not prevent the sentence of kipa from being carried out. In contrast, according to Rivash (DH Teshuva) that kipa is a Chumra of Chazal, it seems logical that Chazal would not apply this chumra even where the offender did genuine teshuva.
2) This is not a simple question, but I would like to cite a source which may help us to understand it a little better. This is from the Toras Chaim here, who comments on what Resh Lakish learns (about half way down the page) that the din of kipa is hinted at in the verse (Tehilim 34:22) "bad shall kill the Rasha". Toras Chaim writes that "bad", "ra'ah" refers to suffering, yesurin. This is why someone who has a chazaka of being a rasha, because he received lashes twice, as stated in the Mishna, and then did it a third time, is put in the kipa. He is worse than the standard case of death by Beis Din, who only did the transgression once. The criminal who did it 3 times is deliberately given suffering.
1) I found a source, bs'd, that teshuva is effective for the person sentenced to the kipa. This is from Targum Yonatan to Vayikra 27:29. The Torah there states that any cherem which is made of a person cannot be redeemed but he must surely die. Targum Yonatan translates that if a person has been separated, he cannot be redeemed with money. The only way that he can be redeemed is by offering sacrifices and asking for mercy from Hashem.
2) Kli Chemdah (Parshas Shoftim on Devarim 17:6, page 104, second column) writes that Targum Yonatan is referring to someone who killed without receiving prior warning not to do so. He cannot be killed by Beis Din because he had not been warned, so he is sentenced to the kipa. Targum Yonatan teaches us that paying money cannot buy him free, but if he does a complete Teshuva he is pardoned. If the Beis Din see that he has done teshuva with a complete heart, they do not place him in the kipa.