Belgrade, Serbia-Montenegro ? An arrest warrant was issued Friday for the wife of former Yugoslav President Slobodan Milosevic in connection with the murder of Milosevic’s predecessor, a police source said.

Mirjana Markovic, an unpopular figure in Serbia widely known as “the red witch” for her strong influence on Milosevic, left the country weeks before last month’s assassination of Serbian Prime Minister Zoran Djindjic.

The investigation into Djindjic’s assassination uncovered Markovic’s alleged connection to the earlier murder of former Serbian President Ivan Stambolic.

Markovic is believed to be in hiding in Russia, and Serbia is expected to ask for her extradition. In a letter released Monday, Markovic denied being involved in Stambolic’s killing, calling the accusation “heinous” and politically motivated.

The source, a ranking police official who requested anonymity, refused to be more specific about why police were seeking Markovic’s arrest.

But police have accused her and Milosevic of being behind the 2000 murder of Ivan Stambolic, Serbia’s president for a year in the mid-1980s.

Stambolic was preparing to challenge Milosevic in presidential elections when he was abducted while jogging in a Belgrade park in August 2000.

His body was found last week on a northern Serbian mountain by police investigating Djindjic’s assassination. He had been shot to death.

An elite police unit with ties to organized crime is suspected in the killings of both Stambolic and Djindjic. The unit, formed by Milosevic, was disbanded last month.

Djindjic, who was instrumental in Milosevic’s extradition to a U.N. war crimes tribunal in The Hague, Netherlands, was shot to death March 12 by a sniper in front of government headquarters in Belgrade.

Police have rounded up 7,000 suspects, including Milosevic-era officials and paramilitaries, on charges they were involved in the assassination or in other crimes.