If Dorner was doing any sort of inside job, they can't leave loose ends, can they?
Even just because he shot an LAPD officer: they never would have let him live to see a trial.
Dorner wasn't doing an inside job. He was a whistleblower exposing LAPD's routine prisoner abuse and culture of jackbooted thuggery.
After exhausting legal remedies available inside the system, he merely served LAPD some of the same 'street justice' they wantonly dish out.
Of course that wasn't acceptable to the thug pigs and they threw a giant tantrum, shooting completely dissimilar citizens in the effort to protect the named-and-shamed dirty cops targeted by Dorner for payback.
They finally burned him alive, assuring he'd never have a chance to write a tell-all book or otherwise pursue exposure of their corruption.