The precise circumstances surrounding the death of Kim Jong-il are a little hard to determine. The notoriously secretive nation of North Korea doesn't release any information about the health of its leaders, whom it treats as living deities. It's believed that Jong-il passed away after suffering complications from a stroke, but it's likely nobody other than his immediate family will ever know for sure.
We can provide some date context to this picture, though. It was taken at a supermarket in Pyongyang on December 14th, 2011. Three days later, North Korea confirmed that Jong-il had passed away, and entered a state of mourning. Ill health may explain why he appears to look a little frail in this final image. His son and successor Kim Jong-un is visible behind him on the staircase, having perhaps been summoned home to North Korea because his father knew that his death was imminent.