This is often a challenge. But fortunately there are some great resources out there. War crimes research often delves into associated topics such as human rights, treaty research and genocide. Try to get some context before you start your research quest.
For current events try consulting news papers and blogs.
JURIST (http://jurist.org) is a web-based legal news and real-time legal research portal powered by a mostly-volunteer team of over 60 part-time law student reporters, editors and Web developers led by law professor Bernard Hibbitts at the University of Pittsburgh School of Law in Pittsburgh, Pennsylvania, USA. It offers access to domestic and international news.
The search "war crimes" in this portal will retrieve several articles what you may want to explore further.
Once you narrow down a writable topic you can start your legal research quest to locate authoritative legal resources on the topic you plan writing on.