you stand behind all the statues
You can't turn them off. You have to slip past the Security room and the lasers in the Statue Room when you enter the museum at night. Hide behind the statues until the lasers move away, then work your way slowly to the door at the left side.
You have the picture that shows how to move the features on the Dragon Face, and you have the key to the Supply Room. Duck past the Security Room, and hide behind the statues to avoid the lasers in the Statue Room.
Duck behind the statues, then move right when the lasers move away. When you get close to the door, go out into the gallery.
When you first enter the room, wait for the laser to go away and run behind the fist statue, then keep going behind the statues dodging the laser.
Although you slip past the Security Room and dodge the lasers in the statue room, you are supposed to be caught at the painting (The Scream). Later, when someone else actually steals it, you have to help catch them.
Avoid the moving lasers by hiding behind the statues, and make your way to the right when they move away. Eventually you can make a run to the gallery door.
When entering the museum at night, you slip past the security office and then avoid the lasers in the statue room. When you reach the painting, jump onto it. This may not seem wise, since you immediately get caught...but it is the next step in the quest.
Break into the museum through the supply room hatch (the dragon face). Slip past the security room and past the lasers in the statue hall. Now you can climb up on the light and jump down to surprise the thief. (Not the best plan, and it wasn't your idea.)
Hid behind the statues and/or plants.It is too dark for the cameras to see you. The things to avoid are the female security guard in the office, and the lasers in the statue room. (Hiding behind the statues works.)
You enter the museum, open the supply closet door, slip past the Security Room, and hide behind the statues to avoid the lasers in the statue room. Make your way to the main gallery and climb the light where The Scream is hanging.
Enter the museum through the dragon face hatch, exit the Supply Room, and slip past the Security Room. Then you cross the Statue Room by hiding behind the statues when the lasers go across. Go to the painting "The Scream" in the main gallery.
Once you duck past the Security Room, and hide behind the statues to avoid the lasers, exit through the doorway at the right and go to the painting The Scream in the gallery.