Moving in the direction of a gun, an alligator can carry out a murder once it reaches it. This alligator wants to kill someone. The alligator wants to carry out their execution.
In order to carry out this murder, the alligator has to sneak up on its prey, so it can shoot it. You look across the water and see a sheep (し) grazing by the shore. The alligator is going to carry out a murder on that sheep!