Per the title, D.H.Q. stands for 'Detective Headquarters'.
Last show of the series.
Although William Boyett was, at the time, portraying the character of Sgt. "Mac" MacDonald on Adam-12, another series directed & produced by Jack Webb, he appears here as Sgt. Art Green, in this last episode of the Dragnet series. The first name of his character is not mentioned during any dialogue, but is listed in the closing credits.
Although Gannon & Friday begin an initial investigation of a purse snatch, in narration, Friday mentions that they later handed the case off to Divisional Detectives. He also mentions in later narration that the other Detectives had hit a dead end. There is also no mention of this case or any resolution, in the closing narration of the program, when the other cases are dealt with & none concerning the man who came to Division Headquarters & reported to Gannon & Friday about being robbed of his money that he had made from collecting & turning in bottles.