Sometimes, we get curious about what has happened. You are there for your friend, and not to satisfy your curiousity. If your friend wants to share, let him and if he doesn't, just be present and respectful to the pain of his loss. In grieving, some people prefer to be doing things, stay with their emotions or both. Do what feels right for your friend. Restrain from saying things like "pain will heal all wound", "don't cry and just move on", "you should be crying", "he's in a better place". These are commonly said words as we don't know what else to say but these can sound dismissive of the loss.