2. Question: For allowing a woman to get remarried why is a person reliable even if he only saw the dead guy by the light of a candle or the moon at night but if a non-Jew or Jew would say that they saw a dead guy at night by the light of the candle or moon and he was just speaking masiach lifi tumo he is not believed?
A. The Shulchan Aruch (Even HaEzer 17:22) says that when you look at the body to recognize it in order to testify about it, one can even check and see it at night by the light if a candle or the light if the moon.
B. The Pischei Teshuva (91) is in fact in doubt whether a person who while just telling over a story happens to have mentioned (unintentionally), mesiach lifi tumo, happens to say he saw a man killed or dead when he was walking at night, by the light of a candle or the light if the moon.
Answer: If a person is testifying he is trusted to be sure to get a good look at the body. But if he is just telling a story, even though masiach lifi tumo is normally believed but because of the circumstances it was dark maybe he didn’t pay close enough attention and he saw wrong.