If [in the process of clearing the debris,] they [reached] his nose and saw that he was not breathing, he should be left there, for he has died already.
Although it is discovered that people on the upper level of a landslide have died, one should not assume that those on the lower levels have died. Instead, [the debris] should be cleared away from all of the people, for in a landslide it is possible that those on the upper level will die, while those on the lower level will remain alive.

A corpse does not impart ritual impurity until the person actually dies. Even if one's veins have been cut, or he is in his death-throes, even if his two vital signs have been slit, he does not impart ritual impurity until his soul expires, as ibid.:13 states: "The soul of a man who dies...."
If his backbone is broken together with most of the surrounding flesh, he was torn apart like a fish from his back, he was decapitated, or he was cut in half from his stomach, he imparts impurity, even though some of his limbs are still making convulsive movements.

Even if they find him trampled and he can only live a few hours, they check his nose, and if they feel no life, he is for sure dead. [They must do this] whether they uncover his nose or his legs first.

5. If she dies while in labor, we bring a knife even through the public domain on Shabbat and cut open her stomach to remove the fetus, in case it is found to be alive. Rem"a: We do not even do this on weekdays because we are not skilled at identifying the mother's death soon enough such that it is possible that fetus can be alive (Issur v'Heter).

One whose neckbone and the larger portion of the surrounding flesh was broken, and likewise, one who was torn up along the back as a fish, even if he is still living, is regarded as dead and defiles [through overshadowing]. But a dying person and one in whom both organs were cut, or one who is wounded [with] many [open] wounds, do not defile [men or vessels] until their soul departs. Nevertheless, it is forbidden [for a Kohen] to enter a house in which there is a dying person, and some permit, and it is proper to adopt the stricter view.