Interesting admission in today's WT: Adam may have understood "day" (as in "in the day you eat from it, you will positively die") to be a literal 24-hour period. I don't think the WT has ever said this before; the usual emphasis is that Jah meant it as a figurative day, a day from his standpoint which is 1,000 years (and the article does state that, later).
However, if Adam understood God's warning to be carried out in a 24 hour period, and God did nothing to alleviate that, then who did the lying? Actually, regardless of Adam's understanding, the question still stands but moving toward an admission of the use of day in that context to be 24-hours only makes the question even more valid. The article tries to explain things by saying that God mercifully allowed Adam to Eve to live longer in order to have children, but that doesn't change the plain fact that it was God lying, not Satan.
Satan said three things would happen if they ate: (1) Eyes opened; (2) Be like God; (3) You will not die. He didn't add any kind of temporal aspect to the last, but it would be understood in the same way that God's threat would be understood. According to the WT, in this article, it would be understood as a 24-hour day. And what happened? Each of the three things took place, exactly as Satan said they would. Moreover, God's words later in Ch. 3 of Genesis imply that Adam and Even wouldn't die AT ALL if God didn't take action to prevent them from eating of the Tree of Life.
No, I don't believe that Genesis is a literal history. My point here is that the WT's interpretation just doesn't fit the account as it is written, and is another example of eisegesis at its finest.