DAKAR, Senegal — Preliminary evidence collected against former Chad President Hissene Habre could lead to charges of war crimes, crimes against humanity and torture, according to the prosecutor at a special court established more than 20 years after Habre fell from power.

Judges will decide on Tuesday whether to formally charge Habre or to extend his provisional detention by 48 hours, prosecutor Mbacke Fall said at a press briefing Monday.

Habre ruled Chad from 1982 to 1990. Human rights and victims groups say that soon after coming to power, he promoted members of his Gorane ethnic group to head a ruthless torture and killing apparatus targeting members of other ethnic groups that threatened his rule.

He was removed from office in 1990 in a military coup, fleeing to Senegal. Over the next 20 years, as Senegalese authorities resisted attempts to try him, Habre became a symbol of impunity and an uncomfortable reminder of Africa's unwillingness to hold its leaders accountable.

The Extraordinary African Chambers court was finally inaugurated earlier this year, paving the way for Habre's prosecution, which could occur as early as 2014 if an indictment is formalized.

In May 1992, a 10-member Chadian truth commission formed by then-new President Idriss Deby reported that Habre's government was responsible for an estimated 40,000 deaths.

The commission placed particular blame against the Directorate of Documentation and Security, Habre's political police force, which "distinguished itself by its cruelty and its contempt for human life," employing torture methods that included whippings, beatings, burning and the extraction of fingernails. One technique involved forcing a victim to put his mouth around the exhaust pipe of a running vehicle, causing severe burns when the motor was accelerated.

Fall said Monday that the court's investigation had turned up considerable evidence involving the DDS. "This oppressive mechanism had a mission to secure the country against espionage and exterior attacks. But it was completely transformed into an element of terror," he said.

Habre's Senegalese lawyer El Hadji Diouf has disputed the allegations against his client. Standing outside the Extraordinary African Chambers on Monday, he said all of Fall's evidence was incorrect.