Deleted Scene Robbed Star Wars Fans Of a Perfectly Dark Twist
One of the common criticisms of the Star Wars prequel trilogy was both of Palpatine's earlier apprentices, but especially Count Dooku, failing to live up to their potential, with relatively minor roles and little agency.
Revenge of the Sith official novelization even played with that idea, portraying Dooku as an arrogant, snobbish villain, whose biggest shock in life – a few moments before his death – came from the belated realization that his chief role in Palpatine's master plan was getting killed by Anakin.
But Dooku was not always supposed to have such a minor role in the story, as one of the deleted scenes from Episode III proves.
That scene must have been rejected early in the production, unlike some scenes which got cut from the theatrical version of the movie, but were actually filmed, and later included into DVD/Blu-ray releases. It was only mentioned in 2005 book The Making of Star Wars Revenge of the Sith.
During Anakin's fight with Dooku, Palpatine was supposed to say, "Anakin, he was bragging earlier about how he arranged to have your mother killed by the Tusken Raiders," and Dooku was supposed to confirm that before continuing the fight (via).
In the final version of the trilogy Anakin's mother death happens as a tragic accident, and even though at that point Palpatine already was closely monitoring Anakin, there is nothing to suggest that any of his underlings had any role in her death, or in fact that Palpatine or Dooku even knew where to find her.
And while changing that could have been a surprisingly dark twist, is fairly easy to guess why this revelation got cut: it did not really change anything in the scene, while making the extent of Sith manipulation throughout Anakin's life much more tighter, thus reducing his own responsibility.
And while such a dramatic villainous confession was perhaps appropriate for space opera, it also was sort of stupid. Even if Dooku also wanted to turn Anakin to the Dark Side, instead of just killing him then and there, doing so by making Anakin extra mad at him specifically does not sound like a good plan.
Count Dooku always had a presence of a composed, calculating villain, and Episode II all but directly stated that he was already scheming against his master, as a proper Sith ought to. Playing along with Palpatine in this situation would have been out of character for him.