I am seeking information on Ollie Estes, a policeman in OKC who may have become police chief.

You might wish to pick up a copy of "Oklahoma Justice" by Ron Owens. It is a history of the OK city PD ,probably the best police department history book every written. If I remember correctly no one by that name served as Chief.He is pictured in the book in at least one image as a policeman.

Ron Owens' great history of the Oklahoma City Police Department, entitled "Oklahoma Justice", has a couple of references to Ollie Estes. There's an article on page 59 (dated 3/31/1911), concerning Estes being chosen as one of the "first" motorcycle officers added to the force; and, on page 70, there's a group photo of the 1916 OCPD. Ollie Estes appears 4th row from the top, 3rd person from the left. (very good, sharp photo!)

I don't believe that he ever became "Chief" of the Oklahoma City Police Department.