Among the victims of Jolly Shaju's string of poisonings were her husband, her in-laws and a two-year-old child.
The devices use bait to lure wildlife before releasing deadly sodium cyanide into the mouth of any animal that takes a bite.
There is no known antidote to the poison, which is around 1,200 times more toxic to humans than cyanide.
The clouds triggered a four-year cold snap. Talk about "winter is coming."
The envelope reportedly contained a milky substance and was in a container wrapped in a plastic bag.