The idea that your life (or someone else's life) is being threatened in a dream merely explores non-integrated qualities as you move through change. As you go though major changes, you must allow outworn aspects to 'pass on,' as part of your identity of the past may need to 'die away.' At the same time, being pursued by a murderer can portray one aspect attempting to kill off another, not always beneficial and so the symbolism surrounding the murder needs to be explored. If someone is 'assassinated' then you must consider whether you are doing something that is, perhaps, assassinating your character. See Corpse and Attack or Being Chased.