Once blackmailers see that their target's guilt can serve them, time becomes irrelevant. If there's no recent incident to peg their guilt and blame-peddling on, one from the past will do just fine. There's no point at which a guilt-producing event is allowed to diminish and reparations are considered fully made. Blackmail targets discover that whatever their real or imagined transgression may be, there is no statute of limitations -- no point after which an ancient "crime" ceases to be an issue, or a punishable offense.
-- Susan Forward with Donna Frazier, Emotional Blackmail, p. 56