Belgrade, Serbia-Montenegro ? There are “credible suspicions” the wife of former President Slobodan Milosevic was involved in the murder of her husband’s predecessor, and she must return from Russia immediately for questioning, Serbia authorities said Saturday.

The alleged involvement of Mirjana Markovic in the 2000 disappearance and killing of former Serbian President Ivan Stambolic was uncovered by police investigating the March 12 assassination of Prime Minister Zoran Djindjic.

Serbia’s Interior Ministry said police were “searching intensely” for Markovic, citing “credible suspicions of her involvement in the murder” of Stambolic.

An order to detain Markovic for questioning was issued Friday, shortly after police found the remains of Stambolic, a Milosevic foe who led Serbia during the communist era and disappeared in August 2000 while jogging in a park.

After questioning two of Markovic’s associates — officials from her neo-communist Yugoslav Left party, police learned Markovic left the country Feb. 23 and currently is in the Russian Federation.

Authorities informed Markovic’s lawyers that an international warrant for her arrest would be issued unless she returned immediately.

Milosevic’s brother, Borislav, a former ambassador to Russia who lives in Moscow, refused to comment.

The discovery of Stambolic’s body, shot with two bullets and thrown into a lime pit in northern Serbia, came as police questioned thousands of Milosevic-era war veterans, drug traffickers and various underworld figures while investigating Djindjic’s murder.

That investigation shed light on the unsolved Stambolic case.

The Interior Ministry called Markovic a “person of utmost political influence” at the time of Stambolic’s murder, but did not elaborate on specific details of her alleged involvement. No formal charges have been brought.