It's fairly standard detective work, I think, to try to trace back
any item left at the crime scene, attempting to narrow down the list of potential suspects; I don't really have a problem with that (as others have mentioned, they'd do the same with a shoe or whatever).
I think the big question is what is done with the rest of the data afterwards: if they just stick the list in a file drawer and ignore it unless and until they have similar hard evidence of another crime being committed with the same model of knife, that's fine, too. The concern would be if someone in the police department (or mayor's office, or a local reporter, or "concerned citizen's" group) gets the "bright idea" that they should start investigating everyone else on the list, figuring that the rest of them must be a bunch of shady characters too (leading us back into the whole push of "people don't do bad things, inanimate objects do"
).
After all, "everyone" knows that only a bad,
dangerous, person would own a "commando" knife, or an expensive knife, or a pocket knife, or ... a kitchen knife, or a screwdriver, or a stick, or a blunt object of any kind, or a car, or ...
The average Joe Sixpack, with a long history of getting their information misquoted to them from the average TV reporter, won't think along
our lines of "what a terribly
dreadful use of such a nice knife"; instead they'll be "terrified and angered to learn that evil companies are making vicious weapons of mass destruction specifically tailored to the needs of felons" ("and we alerted you to this danger first, Film At 11").
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Carl /\/\/\ AKTI #A000921 /\/\/\ San Diego, California
Think this through with me ... Let me know your mind
Wo-oah, what I want to know ... is are you kind?
-- Hunter/Garcia, "Uncle John's Band"