Do you think her behavior is a direct link to her JW-ness? Or do you think she is just deceptive aside from her upbringing.
I wasn't raised as a jw, but I have been associated with them for most of my adult life and I would say that the lying is built into the religion. When you are convinced that everyone outside of your small (by comparison) organization is wicked and a tool of your worst enemy, satan, then lying becomes a rather small thing.
The jw cult inculcates a learned paranoia into their members. You not only fear the wicked people outside the organization, but you fear your brothers and sisters too because some of them are going to become bad association and could lead you away from god. *begin sarcasm* Noboby knows which ones will turn out to be a false brother and sister, but luckily most in the congregation have some pretty good guesses that they are willing to share to those they trust. *end sarcasm*
But it isn't just the wicked world and potential false brothers that the jw learns to fear, it's god and jesus themselves. They teach that if you don't show proper respect to the organization and obey it implicitly, you will be offending god and could be thrown out of the organization or destroyed.
Finally, each witness is taught to not trust themselves either. Since each heart is treacherous, you can't even trust your own intuition, motives, desires, and dreams. You basically have to maintain a wall a fear from all sides and from all people. It's quite taxing and with this much pressure, oftentimes it's just easier to lie.