I have recently been informed that Ziva David is presumed dead. I say presumed dead because of the stuff like Tali being perfectly fine and Ziva's body not being found. I began to ponder how Ziva has changed as the series went on, from noticeable visual changes to subtle emotional changes. This is what I noticed.
When we first meet Officer David, we meet a mysterious Mossad Liaison that seems to have a mystery around her. When she ultimately reveals her purpose in being in America, it is met with disbelief and distrust by most. There are a few exceptions to this, one being Gibbs. The young woman who walked in as Officer David had soft, curly hair with an innocent demeanor. Hidden in her actions and her eyes was a subtle insecurity and venerability. She seemed to be functioning on loyalty to her country but not knowing exactly why. As the series progressed, and the team fully accepts her and she becomes one of the team, you see this understanding of what exactly she is working towards, a full understanding, and with it, confidence. She has people who truly care for her, and she will fight to keep that. There are setbacks, however, and the ultimate crash seems to be Somalia, and Rivken. She has seemingly lost what she started with, and with that, begins to question what she has now. Her father Eli's sudden reappearance and subsequent death toss her deeper into the pit she has worked so hard to get out of. She departs NCIS mostly free of Mossad, and goes to Israel to search for answers. The old insecurities have come back, and Ziva wants nothing to do with anything related to her past. Tony goes after her, and now we meet Tali, who is her and Tony's daughter. This shows that she has somewhat begun to recover. I am not going to assume she is dead, because Ziva being a mother knows better than that, especially with her past. The apparent death is not her style, and the circumstances surrounding it are too suspicious.