Mourn the loss of someone who was just walking along and got stabbed. Don't adopt the lame argument of "He got killed, just doing his job as a cop.". Putting themselves in the line of fire.
Why? Everyone knows anytime you leave the house you run the chance of getting killed in any number of ways. They made the choice to do it, so they shouldn't be mourned. The only people that whould be mourned apparently are people who get murdered while sleeping, but even that, they know when they sleep that they're vulnerable, they made the choice to sleep, so I guess we shouldn't mourne them either. Mourne no one.
Oh wait, maybe we can mourne babies, they didn't choose to be borne, so if they die it's not really their fault.
Then again, they did choose to try and swallow that fork...