We cannot tell from the text was was written; until we come to be able to ask Jesus himself, I suspect we will never know.
However, the text does give us other details to consider:
If the woman was truly taken “in the very act” of adultery, why was only the woman brought? What happened to her partner, since this sin is one that, by definition, cannot be committed alone?
If they allowed one sinner to escape, and dragged another off publicly for punishment and shame, is that not being unjust?
If they want to change their story, are they not guilty of lying–or, in this context, perjury, since they are asking Jesus to act as judge?