In my personal humble opinion, the Libyan leader should have been tried before executed. His execution only spurs speculation that there was something the rebels didn't want the world to know. In other words, his immediate execution was meant to "silence him."
Here is the Muammar Muhammad Abu Minyar al-Gaddafi's final moments before he was brutally killed by the Libyan rebels.
Gaddafi was found hiding in a hole in the ground and had said "Don't shoot, don't shoot" to the men who grabbed him.
His capture followed within minutes of the fall of Sirte. The once proud Libyan leader who decorated himself in fabulous suits now looks like a beggar. He was mauled and spat on and was put into the hood of a vehicle, where the bloodstained deposed leader pleaded for his life. Moments later, he was dragged into the ambulance, and the Libyan leader was no more. Gaddafi endured physical injuries from the mauling, but what took his life was a gunshot wound in the abdomen, and on the head.
Now, here's a question to all. What's the difference between Libya ruled by a tyrant and Libya ruled by barbarians?