SANTIAGO, Chile — A judge Monday ordered Augusto Pinochet to undergo psychiatric and neurological tests later this week to determine whether the former Chilean dictator can stand trial on charges of human rights abuses.

Judge Juan Guzman determined that the tests be conducted Thursday by three doctors at Pinochet's suburban Santiago mansion. Guzman made the decision after questioning Pinochet on Saturday about the disappearances of 24 dissidents while he was in power from 1973 to 1990.

The judge, defence lawyers and lawyers for the victims' relatives each get to pick one of the three doctors.

Guzman is investigating Pinochet 's role in the so-called Operation Condor, a joint plan by the authoritarian regimes ruling several South American countries in the 1970s to suppress dissent. Twenty-four Chileans were allegedly killed or made to disappear in the operation, according to new court papers disclosed Monday.

Pinochet's lawyers insist the 88-year-old retired general's health makes him unfit to stand trial, as ruled by the Supreme Court in 2001, when Guzman indicted Pinochet in a different human rights case and kept him under house arrest for 43 days.

Pinochet has been diagnosed with a mild case of dementia, suffers from diabetes and arthritis, and has a pacemaker for his heart.

If doctors determine Pinochet's health allows him to face trial, Guzman will be free to again indict him, as Pinochet was stripped by the same court of the immunity from prosecution he enjoyed as a former president.