1) a random citizen murders someone and
2) a cop murders someone on duty?
Yes, ideally the country would be safe enough that no one was killed, and you can even argue that it don't matter because the end result is the same (hell, some people would even argue whoever the police kills had it coming). But most people understand that when those entrusted with special powers for the public good abuse that trust and engage in criminal behavior, it’s a far more serious issue.
1) a random citizen murders someone and 2) a cop murders someone on duty?
Yes, ideally the country would be safe enough that no one was killed, and you can even argue that it don't matter because the end result is the same (hell, some people would even argue whoever the police kills had it coming). But most people understand that when those entrusted with special powers for the public good abuse that trust and engage in criminal behavior, it’s a far more serious issue.