No. Even ignoring the immorality of this choice, you are committing the broken window fallacy. One, the resources spent on countermeasures against the serial killer are resources unavailable for other things. Two, the countermeasures are incapable of negating the negative impact of the serial killer, only diminishing them. Buying countermeasures to protect yourself might be better, economically speaking, than taking your chances with the serial killer, but it will always be worse than not needing to buy the countermeasures in the first place.
The Beltway Sniper(s) had a definite adverse impact on restaurants in the DC area. And since John Muhammad targeted a lot of shopping centers with Michael’s Art Supplies (We’ll never know what inspired that particular common thread), I’m guessing they lost some revenue while he was at large.
Next to the notification centre (below right on your screen) there’s an “EN” which is the language setting. Sometimes you can accidentally click on that. Mine was EN and Chinese. Not helpful at all.
This assumes that, for instance, someone buying a gun or security system would have used the money to buy other things, rather than just holding onto it.
I can see there could be localized economic damage from a prominent serial killer case, certainly (going back to the Boston Strangler case once more, there was a bad impact on door-to-door salesmen, who had a terrible time getting women to open their doors while the panic was on. I imagine that the Encylopedia Britannica saw its sales plunge in the Boston area.).
Well, he was crafty.