No they didn’t need Dorian to confirm the robbery — they had the video tape and other witnesses.
And the Chief said that he was not involved.
He may have known that his buddy stole the cigars but he had no hand in it.
Maybe you know the law then: if you and your buddy walk into a store and your friend robs it. You both leave with the merchandise.
Are you not technically complicate in that robbery?
I think they felt it was not worth persuing.