Is animal beef gelatin halal, despite not being certain that the animal was slaughtered according to Islamic law?

In summary, regarding gelatin: If its source is plant-based or from an animal slaughtered according to Islamic rites (dhabiha), then it is pure (tahir) and permissible to use. If its source is pork, carrion, or an improperly slaughtered animal, then it is forbidden (haram) unless there is a permissible necessity. However, if its origin is unknown, the apparent ruling is that it is permissible to use due to widespread affliction (umum al-balwa) and the unknown origin, and because most of these substances undergo a transformation of their essential nature (istihala), and because the basic principle concerning things is permissibility (al-asl fi al-ashya' al-ibahah). Nevertheless, it is more cautious to avoid using it for those who are not compelled by necessity or can find a permissible alternative.