Will a mother cat ignore her kittens if they are handled by humans?
Someone said because a liiter of kittens were handled, that is why they died, because their mother stopped caring for them. They were strays and were left outside in the pouring rain. After that rain the next day they were dead.
This is a rather unusual behavior. Cats usually stop caring for their kittens when they are old enough to look after themselves. Maybe the kittens were old enough.