1. 1 in 3 black people killed by police in 2015 were identified as unarmed [1].
2. In the current example, the black victim didn't resist arrest.
3. Those 500-600 weren't criminals, because you can only say they're "criminal" after a fair trial (oh, sorry, that's something to do with "human rights", if only you could understand what that means).
4. "Not mourning criminals" or not treating them as humans is the primary reason why USA is not compliant with human rights. The reason why it is important to treat assumed criminals as humans is in my point #5.
5. The reason why people resist arrests is because they have absolutely no trust that the judiciary system will judge them fairly. Today, an innocent would rather die than enter the judiciary system [2].
[1] http://mappingpoliceviolence.org/unarmed/
[2] Innocents are cornered into plea bargain, which is 90% of the criminal cases in USA - It means for 90% criminal cases, there was no formal proof that the accused was guilty. I know, they're black, male, muscular and poor, right!? But that doesn't mean they're guilty. https://en.wikipedia.org/wiki/Plea_bargain
So, once again, you "don't mourn criminals, thugs and people who reach for guns when confronted by police", except you ought to mourn the innocent, the weak and the people who are mugged by police, and you should do that because the police also does it to white people, and you have even fewer organizations to defend against that.