When you have 3,000 points go upstairs in the zombie factory using the main steps on the front start area. At the top of the stairs turn around and go around the steps and go back to the back of the room near the sandbags until you see a vanity or dresser object behind a pillar. Open it and take the flamethrower and go around the pillar over to where the steps are located. If you turn left you will find a room and a wall in a protected corner. Go in the corner and use the grenades behind you and your flamethrower to kill.
Added by: Sanzano Jul 12th 2011, ID#256