It is also fair in this case to ask if he would have gotten similar leniency if he was not a cop. Consider: last year a Virginia man named Ryan Frederick got convicted of a higher charge of voluntary manslaughter with 10 years for killing a cop. Frederick shot the cop as he was busting into his house during a no-knock raid after mistaking him for a burglar.
What Mehserle did was a lot worse and a lot more blatant and wrong than what Frederick did. Yet he gets a lower charge with only 2-4 years?
The judge will find as a matter of fact that he used a handgun in commission of a felony in controversion to Penal Code 12022.5. Otherwise known as a gun enhancement. He is looking at at least another three years to be run consecutively with his existing sentance and could get up to 10 more.
He was convicted of involuntary manslaughter, which is lighter still--in fact, the least serious degree of homicide.