(rsbm)
I totally agree. I don't believe it's a fear of a bullet being traced back to killer, I believe the killer used in item very specific that an ME would easily be able to ID (based on impact pattern it left on the head/skull/etc) and in doing so, would be an item that would then alert LE to a particular person or group of persons who would normally used such an item, say, in the course of their job.......or, an item that only a limited # of people would have access to, except perhaps due to the nature of their job. So that causes me to suspect that the killer(s) was some kind of service person........maybe someone who arrived at their home and went to the door wearing (albeit bogus) work clothing, a uniform........something that would increase the likelihood of the Dermonds having no issue opening the door to that person(s). I think, also, that this person was able to lure Mr D out of the home under the guise that there was something on the exterior or the property that he/she wanted to inspect/fix/clean/trim/etc (window washer, clean the gutters, inspect roof, etc). And very possible someone the D's had previous contact/experience with (maybe this killer in the past did work for them but only in an attempt to case the place)........but not 100% did it have to be someone they'd met before................but then again maybe the killer(s) was someone who they'd seen at a neighbor's home doing work for them.
All a killer would have to do is pull up in a van, wear some kind of work clothing....be carrying a clip board or wearing a tool belt.....etc etc.....and lie and say "I was just doing work for your neighbor down the road "so and so" and they mentioned you might need someone to take a look at your "whatchamacallit" and seeing how I'm already out this way there's no charge for me to inspect "x" while I' m already here."
So then...........what kind of tool/implement/object one could use to strike someone in the head to kill them, that would leave a very identifiable imprint in the skull?
IMO