Lebanon requested that Siddiq be extradited, but the French government refused because they did not receive a guarantee that he would not face the death penalty.
In March 2008 Siddiq escaped from house arrest in France, according to French authorities.
Al-Hariri was killed in a bombing that many Lebanese believe was carried out by Syria, though the Syrians have denied any involvement.
Syrian media has reported that Siddiq is wanted for giving false testimony implicating Syria in the assassination.
Three men held in connection with the killing were recently released on bail by Lebanese authorities.
There are only four other suspects being held in custody, all of whom are pro-Syrian generals who were the commanders of Lebanon's pro-Syrian security unit at the time. None of the men have been formally charged yet.
An international court convened in The Hague in March to try suspects in the murder, more than four years after al-Hariri's death.