People stand in front of the government building marking the 16th anniversary of the assassination of the former Prime Minister Zoran Djindjic in Belgrade, Serbia, March 12, 2019. REUTERS/Marko Djurica 

A woman places a rose on the gate of the government building marking the 16th anniversary of the assassination of the former Prime Minister Zoran Djindjic in Belgrade, Serbia, March 12, 2019. REUTERS/Marko Djurica 

People stand in front of the government building marking the 16th anniversary of the assassination of the former Prime Minister Zoran Djindjic in Belgrade, Serbia, March 12, 2019. REUTERS/Marko Djurica 

People stand in front of the government building marking the 16th anniversary of the assassination of the former Prime Minister Zoran Djindjic in Belgrade, Serbia, March 12, 2019. REUTERS/Marko Djurica 

A woman lights a candle in front of the government building marking the 16th anniversary of the assassination of the former Prime Minister Zoran Djindjic in Belgrade, Serbia, March 12, 2019. REUTERS/Marko Djurica 

People hold candles in front of the government building marking the 16th anniversary of the assassination of the former Prime Minister Zoran Djindjic in Belgrade, Serbia, March 12, 2019. REUTERS/Marko Djurica 

Serbians Vladimir Milisavljevic (L) and Sinisa Petric, former members of the Serbian criminal gang known as Arkan's Tigers, talk during their trial at Spain's High Court in San Fernando de Henares October 6, 2014. Milisavljevic, who had been at large since his conviction for his part in the assassination of Serbian Prime Minister Zoran Djindjic in 2003, was arrested in Spain in 2012 with Petric and Luka Bojovic on charges of murder. REUTERS/Victor Lerena/Pool (SPAIN - Tags: CRIME LAW) 

Candles are placed at the grave of late Serbian Prime Minister Zoran Djindjic, during a memorial service marking the eleventh anniversary of his assassination in Belgrade March 12, 2014. REUTERS/Marko Djurica (SERBIA - Tags: ANNIVERSARY POLITICS CRIME LAW) 

Mila Djindjic (2nd R), the mother of late Serbian Prime Minister Zoran Djindjic, attends a memorial service marking the eleventh anniversary of his assassination in Belgrade March 12, 2014. REUTERS/Marko Djurica (SERBIA - Tags: ANNIVERSARY POLITICS CRIME LAW) 

Supporters of late Serbian Prime Minister Zoran Djindjic attend a memorial service marking the eleventh anniversary of his assassination in Belgrade March 12, 2014. REUTERS/Marko Djurica (SERBIA - Tags: ANNIVERSARY POLITICS CRIME LAW) 

Ruzica Djindjic (C), widow of late Serbian Prime Minister Zoran Djindjic, attends a memorial service marking the eleventh anniversary of his assassination in Belgrade March 12, 2014. REUTERS/Marko Djurica (SERBIA - Tags: ANNIVERSARY POLITICS CRIME LAW) 

A woman touches a picture of late Serbian prime minister Zoran Djindjic on his grave during a memorial service marking the 10th anniversary of his assassination in Belgrade March 12, 2013. Laying flowers where a sniper struck, the political heirs of Serb strongman Slobodan Milosevic paid tribute on Tuesday to the murdered reformer who led his overthrow and plotted the pro-Western path that they now follow. It was a gesture loaded with symbolism for Serbia 10 years to the day since the murder of Djindjic, with thousands of supporters expected to march through the capital, Belgrade, in his honour. REUTERS/Djordje Kojadinovic (SERBIA - Tags: ANNIVERSARY POLITICS) 

Ruzica Djindjic, the widow of assassinated Serbian prime minister Zoran Djindjic lays flowers at Belgrade's New Cemetery during a memorial service marking the 10th anniversary of his assassination in Belgrade March 12, 2013. Laying flowers where a sniper struck, the political heirs of Serb strongman Slobodan Milosevic paid tribute on Tuesday to the murdered reformer who led his overthrow and plotted the pro-Western path that they now follow. It was a gesture loaded with symbolism for Serbia 10 years to the day since the murder of Djindjic, with thousands of supporters expected to march through the capital, Belgrade, in his honour. REUTERS/Djordje Kojadinovic (SERBIA - Tags: ANNIVERSARY POLITICS) 

People walk in a silent procession towards Belgrade's New Cemetery to pay their respects at a memorial service marking the 10th anniversary of the assassination of the late Serbian Prime Minister Zoran Djindjic, in Belgrade March 12, 2013. Laying flowers where a sniper struck, the political heirs of Serb strongman Slobodan Milosevic paid tribute on Tuesday to the murdered reformer who led his overthrow and plotted the pro-Western path that they now follow. It was a gesture loaded with symbolism for Serbia 10 years to the day since the murder of Djindjic, with thousands of supporters expected to march through the capital, Belgrade, in his honour. REUTERS/Djordje Kojadinovic (SERBIA - Tags: ANNIVERSARY POLITICS) 

People walk in a silent procession towards Belgrade's New Cemetery to pay their respects at a memorial service marking the 10th anniversary of the assassination of the late Serbian Prime Minister Zoran Djindjic, in Belgrade March 12, 2013. Laying flowers where a sniper struck, the political heirs of Serb strongman Slobodan Milosevic paid tribute on Tuesday to the murdered reformer who led his overthrow and plotted the pro-Western path that they now follow. It was a gesture loaded with symbolism for Serbia 10 years to the day since the murder of Djindjic, with thousands of supporters expected to march through the capital, Belgrade, in his honour. REUTERS/Djordje Kojadinovic (SERBIA - Tags: ANNIVERSARY POLITICS TPX IMAGES OF THE DAY) 

Serbian Prime Minister Ivica Dacic (L) and Deputy Prime Minister Aleksandar Vucic (2nd L) arrive to lay a wreath in a memory of late Prime Minister Zoran Djindjic in front of Serbian government building where he was assassinated ten years ago in Belgrade March 12, 2013. Laying flowers where a sniper struck, the political heirs of Serb strongman Slobodan Milosevic paid tribute on Tuesday to the murdered reformer who led his overthrow and plotted the pro-Western path that they now follow. It was a gesture loaded with symbolism for Serbia 10 years to the day since the murder of Djindjic, with thousands of supporters expected to march through the capital, Belgrade, in his honour. REUTERS/Djordje Kojadinovic (SERBIA - Tags: ANNIVERSARY POLITICS) 

Serbian Prime Minister Ivica Dacic (C) and members of the government pay their respect in memory of the late former Prime Minister Zoran Djindjic in front of the Serbian government building where he was assassinated 10 years ago in Belgrade March 12, 2013. Laying flowers where a sniper struck, the political heirs of Serb strongman Slobodan Milosevic paid tribute on Tuesday to the murdered reformer who led his overthrow and plotted the pro-Western path that they now follow. It was a gesture loaded with symbolism for Serbia 10 years to the day since the murder of Djindjic, with thousands of supporters expected to march through the capital, Belgrade, in his honour. REUTERS/Djordje Kojadinovic (SERBIA - Tags: ANNIVERSARY POLITICS) 

Ruzica Djindjic, the widow of assassinated Serbian prime minister Zoran Djindjic, crosses herself during a memorial service marking the ninth anniversary of the assassination of late Serbian Prime Minister in Belgrade March 12, 2012. REUTERS/Ivan Milutinovic (SERBIA - Tags: CRIME LAW POLITICS OBITUARY) 

Serbia's President Boris Tadic (C) and Ruzica Djindjic, the widow of assassinated Serbian prime minister Zoran Djindjic place candles during a memorial service marking the ninth anniversary of the assassination of late Serbian Prime Minister in Belgrade March 12, 2012. REUTERS/Ivan Milutinovic (SERBIA - Tags: CRIME LAW POLITICS OBITUARY) 

Serbia's President Boris Tadic (R) and Ruzica Djindjic, the widow of assassinated Serbian prime minister Zoran Djindjic place candles during a memorial service marking the ninth anniversary of the assassination of late Serbian Prime Minister in Belgrade March 12, 2012. REUTERS/Ivan Milutinovic (SERBIA - Tags: POLITICS OBITUARY) 

An unidentified man waves to Serbia's President Boris Tadic (R) and Ruzica Djindjic, the widow of assassinated Serbian prime minister Zoran Djindjic as they leave the cemetery after a memorial service marking the ninth anniversary of the assassination of late Serbian Prime Minister in Belgrade March 12, 2012. REUTERS/Ivan Milutinovic (SERBIA - Tags: CRIME LAW POLITICS OBITUARY) 

Serbia's President Boris Tadic (R) and Ruzica Djindjic, the widow of assassinated Serbian prime minister Zoran Djindjic leave the cemetery after a memorial service marking the ninth anniversary of the assassination of late Serbian Prime Minister in Belgrade March 12, 2012. REUTERS/Ivan Milutinovic (SERBIA - Tags: CRIME LAW POLITICS OBITUARY) 

False passports and money confiscated from members of the Balkan criminal underworld are displayed after a news conference in Madrid February 13, 2012. Spanish police have arrested Vladimir Milisavljevic, who had been at large since his conviction for the 2003 assassination of Serbian Prime Minister Zoran Djindjic, the Interior Ministry said on Friday. In a raid on a restaurant in eastern city Valencia on Thursday, police also detained Luka Bojovic, a major player in the Balkan criminal underworld, and Sinisa Petric, also known as "Baku", and described by the Ministry as Bojovic's "chief executor". REUTERS/Susana Vera (SPAIN - Tags: CRIME LAW CIVIL UNREST) 

A reporter takes photographs of weapons confiscated from members of the Balkan criminal underworld after a news conference in Madrid February 13, 2012. Spanish police have arrested Vladimir Milisavljevic, who had been at large since his conviction for the 2003 assassination of Serbian Prime Minister Zoran Djindjic, the Interior Ministry said on Friday. In a raid on a restaurant in eastern city Valencia on Thursday, police also detained Luka Bojovic, a major player in the Balkan criminal underworld, and Sinisa Petric, also known as "Baku", and described by the Ministry as Bojovic's "chief executor". REUTERS/Susana Vera (SPAIN - Tags: CRIME LAW CIVIL UNREST) 

Spanish police general director Ignacio Cosido, Spain's Interior Minister Jorge Fernandez Diaz, Serbian ambassador to Spain Jela Bacovic and Spanish chief police for the unit of violent crimes Serafin Castro Frias (L-R) attend a news conference in Madrid February 13, 2012. Spanish police have arrested Vladimir Milisavljevic, who had been at large since his conviction for the 2003 assassination of Serbian Prime Minister Zoran Djindjic, the Interior Ministry said on Friday. In a raid on a restaurant in eastern city Valencia on Thursday, police also detained Luka Bojovic, a major player in the Balkan criminal underworld, and Sinisa Petric, also known as "Baku", and described by the Ministry as Bojovic's "chief executor". REUTERS/Susana Vera (SPAIN - Tags: CRIME LAW CIVIL UNREST) 

Serbian criminal Luka Bojovic is seen on a television screen upon his arrest as Spain's Interior Minister Jorge Fernandez Diaz (R), general director of Spanish police Ignacio Cosido and head of Spanish riot police Eugenio Pino (L) attend a news conference in Madrid February 13, 2012. Spanish police have arrested Vladimir Milisavljevic, who had been at large since his conviction for the 2003 assassination of Serbian Prime Minister Zoran Djindjic, the Interior Ministry said on Friday. In a raid on a restaurant in eastern city Valencia on Thursday, police also detained Bojovic, a major player in the Balkan criminal underworld, and Sinisa Petric, also known as "Baku", and described by the Ministry as a Bojovic's "chief executor". REUTERS/Susana Vera (SPAIN - Tags: CRIME LAW CIVIL UNREST) 

Spanish police officers stand next to weapons and artefacts confiscated from members of the Balkan criminal underworld after a news conference in Madrid February 13, 2012. Spanish police have arrested Vladimir Milisavljevic, who had been at large since his conviction for the 2003 assassination of Serbian Prime Minister Zoran Djindjic, the Interior Ministry said on Friday. In a raid on a restaurant in eastern city Valencia on Thursday, police also detained Luka Bojovic, a major player in the Balkan criminal underworld, and Sinisa Petric, also known as "Baku", and described by the Ministry as Bojovic's "chief executor". REUTERS/Susana Vera (SPAIN - Tags: CRIME LAW CIVIL UNREST) 

France's Foreign Minister Bernard Kouchner (L) and Ruzica Djindjic, the widow of Serbia's assassinated Prime Minister Zoran Djindjic place a wreath in front of Djindjic's grave in Belgrade March 1, 2010. Kouchner is on a one-day visit to the Serbian capital. REUTERS/Djordje Kojadinovic (SERBIA - Tags: POLITICS OBITUARY) 

France's Foreign Minister Bernard Kouchner (L) and Ruzica Djindjic, the widow of Serbia's assassinated Prime Minister Zoran Djindjic stand in front of Djindjic's grave in Belgrade March 1, 2010. Kouchner is on a one-day visit to the Serbian capital. REUTERS/Djordje Kojadinovic (SERBIA - Tags: POLITICS OBITUARY) 

U.S. Vice President Joe Biden speaks with Ruzica Djindjic, the widow of slain Serbian prime minister Zoran Djindjic, in Belgrade May 20, 2009. Vice President Biden arrived in Serbia on Wednesday on the highest-level U.S. visit in a quarter century, but faced skepticism because of his past support for Belgrade's wartime foes. REUTERS/Marko Djurica (SERBIA POLITICS) 

U.S. Vice President Joe Biden (L) shakes hands with Serbia's Prime Minister Mirko Cvetkovic (R) as Ruzica Djindjic, widow of slain Serbian prime minister Zoran Djindjic, watches after their meeting in Belgrade May 20, 2009. Vice President Biden arrived in Serbia on Wednesday on the highest-level U.S. visit in a quarter century, but faced scepticism because of his past support for Belgrade's wartime foes. REUTERS/Marko Djurica (SERBIA POLITICS) 

U.S. Vice President Joe Biden stands with Ruzica Djindjic, the widow of slain Serbian prime minister Zoran Djindjic, in Belgrade May 20, 2009. Biden arrived in Serbia on Wednesday on the highest-level U.S. visit in a quarter century, but faced scepticism because of his past support for Belgrade's wartime foes. REUTERS/Marko Djurica (SERBIA POLITICS) 

A woman waits in line to pay her respect at a memorial service marking the 6th anniversary of the assassination of late Serbian Prime Minister Zoran Djindjic, in Belgrade March 12, 2009. REUTERS/Marko Djurica (SERBIA ANNIVERSARY CONFLICT SOCIETY POLITICS OBITUARY) 

Ruzica Djindjic, widow of Zoran Djindjic, lays flowers at a memorial service marking the 6th anniversary of the assassination of late Serbian Prime Minister, in Belgrade March 12, 2009. REUTERS/Marko Djurica (SERBIA ANNIVERSARY CONFLICT SOCIETY POLITICS OBITUARY) 

Serbia's President Boris Tadic (C) crosses himself as he stands next to Ruzica Djindjic, widow of Zoran Djindjic, at a memorial service marking the 6th anniversary of the assassination of late Serbian Prime Minister, in Belgrade March 12, 2009. REUTERS/Marko Djurica (SERBIA ANNIVERSARY CONFLICT SOCIETY POLITICS OBITUARY) 

People pay their respects at a memorial service marking the 6th anniversary of the assassination of late Serbian Prime Minister Zoran Djindjic, in Belgrade March 12, 2009. REUTERS/Marko Djurica (SERBIA ANNIVERSARY CONFLICT SOCIETY POLITICS OBITUARY) 

People wait in line to pay their respects at a memorial service marking the 6th anniversary of the assassination of late Serbian Prime Minister Zoran Djindjic, in Belgrade March 12, 2009. REUTERS/Marko Djurica (SERBIA ANNIVERSARY CONFLICT SOCIETY POLITICS OBITUARY) 

People walk towards Belgrade's New Cemetery, during a silent procession, to pay their respects at a memorial service marking the 5th anniversary of the assassination of the late Serbian Prime Minister Zoran Djindjic, in Belgrade March 12, 2008. The banner reads: "Serbia mustn't stand still". REUTERS/Ivan Milutinovic (SERBIA) 

People walk towards Belgrade's New Cemetery, during a silent procession, to pay their respects at a memorial service marking the 5th anniversary of the assassination of the late Serbian Prime Minister Zoran Djindjic, in Belgrade March 12, 2008. The banner reads: "Serbia mustn't stand still". REUTERS/Ivan Milutinovic (SERBIA) 

People lay flowers at the grave of the late Serbian Prime Minister Zoran Djindjic during a memorial service marking the 5th anniversary of his assassination, in Belgrade March 12, 2008. REUTERS/Ivan Milutinovic (SERBIA) 

A girl holds a yellow rose during a memorial service marking the 5th anniversary of the assassination of Serbian Prime Minister Zoran Djindjic in Belgrade March 12, 2008. REUTERS/Ivan Milutinovic (SERBIA) 

People attend a memorial service marking the 5th anniversary of the assassination of Serbian Prime Minister Zoran Djindjic in Belgrade March 12, 2008. REUTERS/Ivan Milutinovic (SERBIA) 

Supporters of assassinated Serbian Prime Minister Zoran Djindjic attend a memorial service marking the fifth anniversary of his assassination in Belgrade March 12, 2008. REUTERS/Marko Djurica (SERBIA) 

(R-L) Serbian President Boris Tadic, Ruzica Djindjic, the widow of assassinated Serbian Prime Minister Zoran Djindjic, and her children Luka and Jovana attend a memorial service marking the fifth anniversary of the assassination of late Serbian Prime Minister in Belgrade March 12, 2008. REUTERS/Marko Djurica (SERBIA) 

Serbian President Boris Tadic (R) hugs Ruzica Djindjic, the widow of assassinated Serbian Prime Minister Zoran Djindjic, during a memorial service marking the fifth anniversary of the assassination of late Serbian Prime Minister in Belgrade March 12, 2008. REUTERS/Marko Djurica (SERBIA) 

Supporters of murdered Serbian Prime Minister Zoran Djindjic wait for the verdict of the trial of his killers in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. The supporters are wearing t-shirts with an iconic image of Djindjic's eyes above his name. REUTERS/Marko Djurica (SERBIA) 

Supporters of murdered Serbian Prime Minister Zoran Djindjic wait for the verdict of the trial of his killers in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. The banners read: "It's not over". REUTERS/Marko Djurica (SERBIA) 

A supporter of Milorad Ulemek, who was convicted of killing Serbian Prime Minister Zoran Djindjic on Wednesday, argues with journalists outside the court in Belgrade May 23, 2007. Ulemek, a former commander of a paramilitary police unit and 11 co-conspirators were found guilty of the assassination of reformist Djindjic four years ago. REUTERS/Marko Djurica (SERBIA) 

A supporter of Milorad Ulemek, who was convicted of killing Serbian Prime Minister Zoran Djindjic on Wednesday, argues with journalists outside the court in Belgrade May 23, 2007. Ulemek, a former commander of a paramilitary police unit and 11 co-conspirators were found guilty of the assassination of reformist Djindjic four years ago. REUTERS/Marko Djurica (SERBIA) 

The wife of Milorad Ulemek, who was convicted of killing Serbian Prime Minister Zoran Djindjic on Wednesday, leaves the courtroom with her bodyguards in Belgrade May 23, 2007. Ulemek, a former commander of a paramilitary police unit and 11 co-conspirators were found guilty of the assassination of reformist Djindjic four years ago. REUTERS/Marko Djurica (SERBIA) 

Supporters of murdered Serbian Prime Minister Zoran Djindjic wait for the verdict of the trial of his killers in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. The banner reads: "40 years is not enough". REUTERS/Marko Djurica (SERBIA) 

A supporter of Milorad Ulemek, who was convicted on Wednesday for the murder of Serbian Prime Minister Zoran Djindjic, makes a defiant gesture as he leaves Serbia's special court after the verdict was read out in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. REUTERS/Marko Djurica (SERBIA) 

A member of a special police unit stands guard at the entrance of Serbia's special court while the verdict was read out in the trial for the murder of Serbian Prime Minister Zoran Djindjic in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. REUTERS/Marko Djurica (SERBIA) 

Serbia's President Boris Tadic (C) arrives in court for the delivery of the verdict in the trial of the murder of Prime Minister Zoran Djindjic in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. REUTERS/Ivan Milutinovic (SERBIA) 

Special police escort the suspects in the murder of Serbian Prime Minister Zoran Djindjic to court for the delivery of the verdict in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. REUTERS/Ivan Milutinovic (SERBIA) 

Members of the special police unit escorts gang members to the entrance of Serbia's special court for the trial of a key suspect in the murder of Serbian Prime Minister Zoran Djindjic in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. REUTERS/Ivan Milutinovic (SERBIA) 

Police stand at the entrance of Serbia's special court while the verdict is read out in the trial of the murder of Serbian Prime Minister Zoran Djindjic in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. REUTERS/Ivan Milutinovic (SERBIA) 

A member of the special police unit stands guard at the entrance of Serbia's special court while the verdict is read out in the trial of the murder of Serbian Prime Minister Zoran Djindjic in Belgrade May 23, 2007. Two former members of a Serbian paramilitary police unit and 10 co-conspirators were found guilty on Wednesday of the assassination of reformist Djindjic four years ago. REUTERS/Ivan Milutinovic (SERBIA) 

A man scrapes off fake street signs bearing the name of Bosnian Serb war crimes fugitive Ratko Mladic which appeared on May 22, 2007, all over a Belgrade boulevard dedicated to Serbian reformist leader Zoran Djindjic. The signs appeared a day before verdicts were due in the trial of the late prime minister's alleged killers. Djindjic was shot dead in March 2003. REUTERS/Marko Djurica (SERBIA) 

A man walks past fake street signs bearing the name of Bosnian Serb war crimes fugitive Ratko Mladic which were plastered all over a Belgrade boulevard May 22, 2007. The boulevard had been dedicated to Serbian reformist leader Zoran Djindjic. The signs appeared a day before verdicts were due in the trial of the late prime minister's alleged killers. Djindjic was shot dead in March 2003. REUTERS/Marko Djurica (SERBIA)