The government doesn't keep figures on how many Americans are killed by illegal aliens (gee, I wonder why) so it's impossible to verify that number. I would be leery of it though.
It would be good thing though to start lobbying state and national congressmen for them to start keeping these figures.
Actually yes they do to some degree. The collect all crime statics from every police department.
And the deaths include all types of deaths including murder.
Suppose we could get the global warming folks to throw a little funding at this?