Where the officer has probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others, it is not constitutionally unreasonable to prevent escape by using deadly force.
https://en.wikipedia.org/wiki/Fleeing_felon_rule
Guess u missed that part
With his violent record and him getting into a car a speeding away...he was a threat of serious physical harm, either to the officer or to others! He would have ran over anyone to get away, could have taken a hostage etc
The POS is dead and will not harm anyone ever again!!!!!