Serbian War Criminal wins legal battle in Manchester Court". The case in Manchester was a challenge to Krstić's status as a Category A prisoner and a decision to continue that status was quashed.
In 2004, Krstić was convicted (on appeal) by the International Criminal Tribunal for Former Yugoslavia (ICTY) of aiding and abetting genocide and was sentenced to 35 years imprisonment which he is currently serving in England. He held high rank in the Serbian military and played a leading role in Krivaja 95. The ICTY website carries details of the case against Krstić and demonstrates the considerable care which the Tribunal took to ensure due process - see here.
The ICTY was set up in 1993 and is the first war crimes tribunal to have been created by the United Nations and the first international war crimes tribunal since Nuremberg and Tokyo. It was established under the United Nations Charter Article VII. Most of the cases before the ICTY have concerned crimes alleged against Serbs and Bosnian Serbs but the tribunal has also dealt with cases against Croats, Bosnian Muslimes and Kosovo Albanians for crimes against Serbs and others. The United Nations has recently extended the life of the tribunal to the end of 2012. Some 37 cases remain on going including that of Radovan Karadžić.
International criminal justice would not be achievable without countries being willing to hold those convicted in prison. The agreement with the U.K. may be seen here. Similar agreements exist with a number of other countries. Over the coming years there will be on-going issues about the status of such prisoners, the security risks involved and eventually questions about parole/early release. Krstić was attacked in Wakefield Prison earlier this year - see Telegraph 8th May.
On the subject of International Criminal Tribunals - there is a challenging book "Fact finding without facts" which considers just how various international tribunals have dealt with this crucial aspect of trials - see Opinio Juris.
See Garden Court Chambers for a report on the Krstić case in Manchester.
Case report - Krstić v Secretary of State for Justice  EWHC 2125 (Admin)