Sifo-Dyas was a real jedi who was a friend of Count Dooku. In this website, it says that count dooku killed sifo dyas under sidious's orders.
Sifo-Dyas was a Jedi Master in the Jedi Order, though he was killed shortly after the time of the Battle of Naboo. The Kaminoan prime minister Lama Su informed Obi-Wan Kenobi that Sifo-Dyas had ordered the creation of a clone army on Kamino to help the Galactic Republic. The Jedi Council was not aware of the order until Kenobi informed them of it after he met with the Kaminoans.
According to the novel : Labyrinth of Evil, Sifo-Dyas was a friend of Jedi Master Dooku, who shared his belief that the Jedi Order was not what it once was and that it shamed itself by serving a corrupt Senate. Dooku, upon beginning his training as Sith Lord Darth Tyranus, was told by his master Darth Sidious that Sifo-Dyas had placed the order for the Clone Army in secret. Dooku was ordered to murder Sifo-Dyas and erase Kamino from the Jedi Archives before he left the Jedi Order for good.
The truth about the Clone Army is left ambiguous- it is possible that Sifo-Dyas indeed ordered it, but it is just as likely that Sidious ordered it and possibly used Sifo-Dyas as a scapegoat, in order to cover his tracks and rid himself of Sifo-Dyas, for reasons unknown. It is possible Sidious felt that Sifo-Dyas's friendship with Dooku could jeopardize his training as a Sith Lord. With Qui-Gon Jinn and Sifo-Dyas dead, Dooku was more likely to be loyal to his new Sith master.