Yevamos 16:2-3

Yevamos 16:2

Let’s say that two women, married to two brothers, returned from overseas and each one reported that her husband died. Neither may remarry because they are blocked by their yibum obligation to the other brother. [While a woman is believed to report that her husband died, she is not believed about her brother-in-law. In this case, each woman’s husband is the other’s brother-in-law.] If one woman has witnesses and the other does not, the one with witnesses may not re-marry (because no one validates her brother-in-law’s death) and the one without witnesses may re-marry (because the other woman’s witnesses corroborate her brother-in-law’s death). If one woman has sons and the other does not, the one with sons may re-marry (because yibum is certainly unnecessary) and the one without sons may not re-marry (because her brother-in-law may still be alive). If the two women were subsequently married by yibum and those new husbands died, they may not re-marry (because each woman can only testify about her own husband but not about the other’s brother-in-law). Rabbi Eliezer says that once we permit them to perform yibum following their first marriages, they are subsequently permitted to re-marry generally.

Yevamos 16:3

In order to identify a body, one must see the face with the nose. This is so even if there are certain small identifiable signs on the deceased’s body and clothes. One may not testify that a person has died until he has actually expired, even if they saw the person being dismembered, crucified or eaten by a wild animal. One may only testify if he saw the corpse within three days of the deceased’s passing (because after that it has changed beyond recognition). Rabbi Yehuda ben Bava says that there are different parameters for different individuals, different locales and different times.