1. The Victim - 23 year old Carlo Giuliani. He squatted in a building in Genoa and worked with the Northeast Social Center. He had good relations with his parents, whom he told he might not attend the demonstrations, saying he might go the beach instead. He had a minor criminal record for insulting a police officer.

2. The police car smashes into a steel garbage bin overturned on the side of the road. Two things occur: The protesters set themselves upon the car and the fire extinguisher is seen clearly, thrown to them from the broken back window. 
It is unlikely the fire extinguisher belongs to the protesters, as it is too heavy to carry while running.
In the background, the carabinieri on the right calls for reinforcements, which are less than thirty meters away.

3. The demonstrator on the left wearing the purple sweatshirt appears to be throwing a stone. The carabinieri in the back, who has his pistol pointing out the back window, points it at him.
Carlo Giuliani (masked, lower right) is standing presumably looking at the extinguisher. He has not yet been seen by the policeman with the pistol.
Meanwhile, other protesters attempt to wedge a piece of lumber into the land rover. 
(Click the picture to enlarge)

4. The protester in the purple sweatshirt has seen the carabinieri pointing the gun at him and attempts to run away from the police car. 
Carlo Giuliani can be seen picking up the fire extinguisher. It seems that the carabinieri holding the pistol has not yet seen Carlo, since he is bent, and another protester is right in front of him. Neither Neither of the protesters in the background with the lumber nor Carlo appear to be aware that the officer has drawn his weapon.

5. Here we see that the protester in the sweatshirt has fallen to his knees. The protesters with the lumber appear to be ready to flee (they have taken the lumber out of the window and have turned around). Carlo Giuliani now has the fire extinguisher in his hands, up in front of his face at the moment in which he is noticed for the first time by the policeman with the gun. This is when the firing takes place.

6. Photo 5 enlarged. Carlo is looking up, he may just have noticed the carabinieri pointing the gun at him. He has the fire extinguisher in his hands, right in front of his face. He is not poised to hurl it, since the position of his arms is clearly not right for throwing - the most he could do is push the fire extinguisher forwards, without much force, considering its weight. 
Even so, the policeman shoots, but not to "defend " himself from Carlo, since in the few seconds that the whole action lasts, several protesters attack the car (at least another one has also been aimed at by the officer) and Carlo is seemingly shot at the very moment he is spotted. 
It seems that it was an indiscriminate act. The carabinieri was ready to shoot any protestor, and Carlo was killed because he was the closest to the car. Besides, if Carlo would have noticed that the policeman had drawn his gun, he would have fled as the others did. 
This was not self-defence, it was murder.

7. Carlo crumples to the ground. Blood is pouring from his left eye, apparently the site of the entrance wound. The force of the bullet spun him around before he fell. According to some reports he received two shots (another one in the forehead) and this is suggested by photo #15. 
Right at that moment another activist crouches to pick up a stone when he notices that Carlo has been shot.

8. The front part of the land rover is still up against the rubbish bin at this point. The protesters flee, worried that the carabinieri may continue shooting.

9. The land rover driver put the car into reverse gear and the back wheel runs over Carlo's stomach.

10. The police car shifts into forward gear and drives over Carlo again, this time over his thighs.
They move forward only a few meters, and many carabinieri reinforcements in full riot gear can be seen. If they were this close to the land rover only seconds after the shot, why was the shooting necessary? Was it also necessary to run over Carlo, a man lying bleeding from head wounds? Note the carabinieri on the left holding his hands to his helmet in shock. The officer who fired the shot is now visible in the back of the vehicle and he appears to be wearing a ski mask.
(Click the picture to enlarge)

11. From this close up we can see that the entrance wound was in the left eye and that the exit wound was likely behind the left temple. 

12. Protesters run forward to Carlo and attempt to staunch the wound in the eye socket. Carlo has already lost about a litre of blood externally, and there is much more internal bleeding in the cranial cavity.

13. Someone has dressed Carlo in something like a shirt. Police and demonstrators keep fighting and a protester tries to remove Carlo's body while another complains about his lack of care.

14. Someone has placed a hankerchief or bandage underneath Carlo's head. 
According to reports, the police and demonstrators fought backwards and forwards over the body for several hours. Note that the clothes of this police riot group are different than the ones from photos 2 and 10.

15. After a line of police is formed in front of the body, sanitary personnel come to Carlo's body. They strip him from the waist and remove his ski mask. The situation is hopeless. A nurse holds her head with her hands suggesting desperation. We can also see here a hole in the forehead, possibly the entrance wound of another bullet. 
(Click the picture to enlarge)

16. Police and carabinieri gawk at Carlo's body. We can see the stomach and thighs out of shape due to being run over. 
(Click the picture to enlarge)