If not hate, then what motivates the killers of old war veterans, infants, and Australian jocks visiting their girlfriend?

http://usnews.nbcnews.com/_news/2013/08/23/20145461-teen-charged-second-sought-in-beating-death-of-wwii-vet-88-in-spokane-wash?lite

http://www.heavy.com/news/2013/08/christopher-lane-murder-oklahoma-baseball-australia/

http://www.huffingtonpost.com/2013/03/23/demarquis-elkins-arrested-baby-antonio_n_2939022.html

When the semi-white George Zimmerman killed Trayvon Martin, the popular opinion was that it was racially motivated, and in fact there is still talk of prosecuting him for a “hate crime”

On the other hand the above crimes are equally, if not more, outrageous, and very few folks are talking about race and hate.

I understand that certain people can not, by modern standards of justice, be guilty of hate crimes.

So, if there is no hate crime in this circumstance, what is the excuse?