The problem with comparing signatures to trademarks is the problem of uniqueness and obviousness.

At a crime scene, something might be present but not necessarily recognized as a trademark and certainly not at the very first victim. A pink ribbon can be present at the crime scene and maybe even tied around the victim, who might be a seamstress or a young girl preparing for a party or the like. It is possible to leave a corpse in a certain position and not have it recognized as having been 'posed' because it just might have been the result of simply tossing the corpse somewhere.