Milan Babic was a key player in the struggle by Croatian Serb separatists to create their own mini-state in Serb-inhabited parts of Croatia in the early 1990s.
By Gabriel Partos
BBC South-East Europe analyst
A dentist by profession, in 1990 he was elected mayor of the town of Knin in the Krajina region - the heartland of the ethnic Serb community.
Babic (right) had been testifying against former rival Martic (left)
This coincided with the rise to power of the hardline Croatian nationalist leader, Franjo Tudjman, and his HDZ party.
As Zagreb began to pursue a range of policies that whittled away the rights
of ethnic Serbs, Mr Babic and his associates established no-go areas for the Croatian security forces.
Fighting escalated during 1991, following Croatia's proclamation of independence, and Serb separatists - armed and supported by the Serb-dominated Yugoslav army - took control of nearly 30% of Croatia's territory.
At the end of 1991, Babic became the first president and prime minister of the self-proclaimed Serb Republic of Krajina, but he was sacked after a few months in a disagreement with Serbian President Slobodan Milosevic over a UN ceasefire proposal.
A year later, he defeated the pro-Milosevic candidate, Milan Martic, in Krajina's presidential election. The result was annulled under pressure from President Milosevic, and a fresh election ensured Mr Martic's victory.
BABIC: RISE AND FALL
1990: Mayor of Knin
May 1991 - Feb 1992: President of Krajina (first an "autonomous region" then a "republic") later foreign minister and prime minister
1995: Flees with other Serbs as Croatian army takes Krajina
2002: Testifies against Slobodan Milosevic
2003: Surrenders to tribunal
2004: Pleads guilty to persecuting non-Serbs, sentenced to 13 years
2005: Loses appeal against sentence
2006: Commits suicide
But later, as the Krajina Serbs' position began to deteriorate and they needed to pull together, Babic re-emerged as Krajina's Prime Minister.
In 1995, he accepted a plan that would have given Serb-inhabited regions considerable autonomy, but it was too late - Croatian forces retook Krajina in a lightning attack in August that year.
He escaped to Belgrade, where he grew mushrooms on land belonging to a relative.
He came to prominence again at the end of 2002 when he testified in Mr Milosevic's trial in The Hague.
He was a key witness for the prosecution which was seeking to prove that although Mr Milosevic, as President of Serbia, had no formal control over events in Croatia, he had the authority in practice to determine the policies of Croatia's hardline Serbs.
He started off as a protected witness, referred to only as C-036, but when hints in his testimony began to point to his identity he opted to go public.
Mr Babic was named in the Milosevic indictment as one of those involved in the ethnic cleansing operations in Croatia, and was eventually charged himself with persecuting non-Serbs.
Initially, Mr Babic refused to plead either guilty or not guilty.
But he took advantage of the 30-day period given to defendants to make up their mind to do some plea-bargaining with the prosecution.
In return for Mr Babic's guilty plea on one charge, the prosecution dropped the other four charges against him.
He also issued a statement in which he expressed shame and remorse for his actions - one of only a handful of defendants to have done that at The Hague.
At the time of his death Mr Babic, who had been spending his jail term at an undisclosed location, had returned to The Hague to give testimony against his former associate and rival, Milan Martic.