I understand the fear of living near such a heinous crime, but you have to see the difference between the two situations. Random crime is scary, but is random. All signs point to this being an assassination. Brian Thompson wasn't the victim of a random criminal, nor was he murdered by some person he has a connection with. He was assassinated. So the right question is why do we investigate assassinations differently than murders? And to me, the answer is clear - an assassination has far larger societal implications than a murder.

Yes, the purpose of an assassination is to have societal implications. In this case, the implications primarily threaten the people in power. Thus, those people direct their forces at preventing and prosecuting such acts.

This is all totally consistent with OP’s charge that there is a two-tiered justice system. Personally, I would much rather see the man who murdered OP’s neighbor in jail than Luigi Mangione.

The average citizen is more at risk of being the victim of random crime than they are being the victim of a targeted assassination.