When you enter the building where you fight Chief Mendez, there is a glitch that will allow you to defeat him with barely any damage. After the short cutscene where Leon blows up Chief Mendez with the gas tank, you will have to fight him. Run up the ladder directly behind to go to the catwalk. Go left and left again on the catwalk. There will be a group of metal boards nailed to the railing on top of the catwalk. If you wait there for about five seconds and remain still, Chief Mendez will just keep walking into the catwalk and not hurt you. Look for a small square cut out of the bottom right corner of the boards. You will be able to shoot him in the face though it but he cannot hurt you. This may not work if you are standing too far to the left or right of the boards. This also only works when he is in his first centipede form.