Question

Hello Rabbi, I’m learning tractate Sanhedrin in depth and I reached the passage dealing with disqualified witnesses. According to the conclusion of Tosafot (and I understood Maimonides this way as well), it seems that the criterion for being considered a witness (and in practice part of the group of the other witnesses as well) is to come testify in religious court. That already doesn’t completely fit the Talmudic passage, but even if we assume it does, seemingly the result is that if the murderer’s brother witnessed the murder, all he has to do in order to disqualify the other witnesses and save his brother is go to court and testify with them. It sounds a bit absurd that one could so easily escape punishment that way. What does the Rabbi think? (It may be that I didn’t understand the passage correctly.)