Belgrade, Serbia-Montenegro ? Authorities said they had “credible suspicions” that Slobodan Milosevic’s wife is linked to the homicide of another Serbian ex-president, and they want her to appear for questioning.

Mirjana Markovic has been in Russia, since Feb. 23, her daughter said. The Serbian Interior Ministry told Markovic’s lawyers Saturday that an international arrest warrant would be issued unless she returned to talk with investigators.

Police uncovered Markovic’s alleged connection to the killing of Milosevic’s predecessor, former Serbian President Ivan Stambolic, while investigating the March 12 assassination of Prime Minister Zoran Djindjic.

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 Belgrade park.

Authorities have detained and questioned thousands of Milosevic-era war veterans, drug traffickers and various underworld figures while investigating Djindjic’s slaying. That investigation shed light on the unsolved Stambolic case, officials said. The Interior Ministry did not provide details of Markovic’s alleged involvement, and no formal charges have been filed.

Interior Minister Dusan Mihajlovic said Friday that members of the elite police Unit for Special Operations, created while Milosevic was in power and active in the Balkan wars of the 1990s, killed Djindjic and Stambolic. The unit was disbanded last week by government decree.

Stambolic was Serbia’s president from 1986 until 1987, when Milosevic engineered a coup and took over the presidency.

After 1987, Stambolic mostly withdrew from politics but was rumored in 2000 to be a possible challenger to Milosevic in presidential elections that year. He then disappeared.