Halakhah su Deuteronomio 17:6

Of even more significance insofar as actual execution of capital punishment is concerned are the rules of evidence governing criminal proceedings under Noachide law. Jewish courts require testimony of at least two credible eye-witnesses for imposition of either corporal or capital punishment. The Bible expressly declares, "At the mouth of two witnesses, or three witnesses, shall he who is worthy of death be put to death" (Deut. 17:6). The testimony of a single witness and, a fortiori, circumstantial evidence, is not admissible.⁵The testimony of witnesses who have actually seen the act may be dispensed with only if culpability can be inferred with absolute certainty from the facts to which eyewitness testimony is presented. For example, Shevu‘ot 46b, states that liability for battery may be established even if witnesses have not observed the act itself provided that the evidence incontrovertibly established (a) that the wound could not possibly be accidental or self-inflicted, e.g., a bite on the back or on the elbow joint; and (b) that no other person was present and hence the defendant must have committed the act. Tosafot, Shevu‘ot 34a, asserts that such evidence may be admitted in capital cases as well. Rambam, Sefer ha-Mizvot, mizvot lo ta'aseh, no. 290, basing himself upon Mekhilta 20:211, regards the verse "the guiltless and righteous you shall not kill" (Exodus 23:7) as an admonition addressed to the Bet Din directing its members not to execute judgment when it is at all possible that the accused is innocent, i.e., when the evidence is circumstantial in nature.

11. A testimony sent in writing to the court is not testimony because the Torah states, “al pi shenayim edim”- it must be from their mouths and not from their writing. This is in fact our custom, not like those who allow it for otherwise valid witnesses who are not mutes.

And Rambam, may his memory be blessed, wrote (Mishneh Torah, Laws of Testimony 3:4) that the main testimony of the Torah is from the mouth of witnesses and not from the mouth of their writing, as it is stated (Deuteronomy 17:6), "By the mouth, etc."; except that because of the betterment of the world, such that people would find [those from whom] to borrow, the Sages ordained that we establish law with regard to money according to witnesses in a deed, the same as from their mouth. But Ramban, may his memory be blessed, (in the Sefer HaMitzvot at the end of the second root) challenged him greatly about this in the Sefer HaMitzvot. And if I would come to write the whole matter, it would be lengthy. But the essence of the thing is that Ramban, may his memory be blessed, holds that the testimony of a deed is from Torah writ, as it is written (Jeremiah 32:44), "write in the book, and seal."