At this point if I were you (and I am not) what I would do if there is another death is put the body in the fridge (not the freezer) and have a necropsy done.

There is no way to know if those death are related or not or what the issue is.

Snakes sometime die for no apparent reason it can be aneurysm, heart diffect, digestive issues etc could that have happen sure.

Could it be something else, it's possible too again the only way to confirm that there is no diseases going on in your collection would be a necropsy.

You mention living in a new place were any chemical sprayed in the snake room?