Dan O'meara has asked me what makes me think Dougherty is taking the assassin(s) down in the elevator. It would be worth your while to read the 1st section, 4 pages, of my 2009 Elevator Escape Theory essay, "The Impossibility of Jack Dougherty's Assassination Aftermath Alibi." He recounted for the Dallas Police that after hearing a shot, he went down to the 1st floor and asked janitor Eddie Piper if he'd heard anything.
Not only was Eddie Piper never asked about this interaction, nor did Piper mention it in his Nov. 23 Sheriff's affidavit- once you check the speed of the freight elevators, you realize that Dougherty couldn't have started traveling downstairs until after Truly & Baker started traveling upstairs, that is until about 2 minutes after the shooting. So his alleged conversation with Piper wasn't a near-immediate reaction to the shots, as was portrayed in his alibi.
He continued to foster that impression, of a near-immediate reaction, in his Dec. 19th FBI statement. Only near the end of Dougherty's Warren Commission testimony does he reluctantly admit that he used the west elevator to go downstairs.
So, Dougherty cut short his lunch break, didn't join his co-workers to watch the motorcade, and obfuscated his movements after his lunch break. He had no good reason to be "getting stock" because he was part of the floor-laying crew. After lunch he went upstairs and then down to the 5th to get stock. The 7th floor was vacant. So he actually was on the 6th floor after his shortened lunch.
Melvin Eisenberg, a junior Warren Commission staff member, was suspicious enough of Dougherty to compose an eyes-only memo entitled "Identity of Assassin". Another junior staff member, Norman Redlich, followed that up with "The Mystery of the West Elevator". My 2015 Inside Job essay details some of their memos on pp. 12-18.
Photographic evidence of the strangers Dougherty took down from the 6th floor is on p. 22 of The Elevator Escape Theory.
Arnold Rowland's man in the 6th-floor west window had dark hair, and Dougherty's hair was blond. I believe Rowland's man was the same man captured in the 6th-floor west window in the Tom Dillard news photo.