Bosnian Serb general Zdravko Tolimir has died in jail in The Hague where he was handed a life sentence for genocide in the 1995 Srebrenica massacre, the Yugoslav war crimes court confirmed Tuesday.
"He died overnight," said an official of the International Criminal Tribunal for the former Yugoslavia (ICTY) who declined to be named.
Once considered the right-hand man of Bosnian Serb army chief Ratko Mladic, Tolimir, 67, was sentenced to life in 2012 for crimes committed "on a massive scale" during the 1990s Bosnian war.
Tolimir's wife Nada Tolimir told Serbia's Kurir newspaper that she learnt of his death late Monday.
"He was ill, but the idiots did not allow him to come here and get treatment at home. I was surprised by the news," the former general's wife was quoted as saying.
In April, the ICTY appeals chamber upheld Tolimir's life sentence for genocide and crimes against humanity and war crimes.
Trial judges described Tolimir as Mladic's "eyes and ears", particularly in the July 1995 massacre at the supposedly UN-protected enclave of Srebrenica, where Bosnian Serb forces slaughtered almost 8,000 mostly Bosnian Muslim men and boys.
The incident was Europe's worst massacre since those committed during World War II.
Mladic himself is on trial at The Hague facing charges including genocide, war crimes and crimes against humanity, including for Srebrenica.
Tolimir was one of the most senior Bosnian Serbs to have a verdict handed down by the UN war crimes court and one of a handful of defendants found guilty of genocide.
He was however not the first top official to die while in the ICTY's custody.
Former Serbian strongman Slobodan Milosevic died in 2006 also while on trial for genocide, war crimes and crimes against humanity.