Could Oswald have been walking east on 10th street (as per Helen Markham) and witnessed the shooting up ahead of him, which had nothing to do with him, and then ran down Patton for his own safety? After which the gunman fled down the same street?
This would explain why Markham thought the man she saw fled down the alleyway that was on Paton street and Callaway thought the man with the gun fled towards Jefferson. Two different men? Markham by her own admission covered her eyes which may have caused her to confuse the two men, thinking that the man she saw, Oswald, had shot Tippit.
Some witnesses say the gunman was walking west along Paton for some distance before the shooting. Markham says he was walking east for some distance before the shooting. A good defense lawyer would make the case that these were two different people, that Oswald had been walking east, saw the shooting up ahead of him and was simply running from the scene of a shooting for his own safety.
First, Markham didn't say the killer was walking east on Tenth "for some distance".
Second, Markham (later) said that the gunman fled in the alley (as opposed to going all the way down Patton to Jefferson). Jimmy Burt and Bill Smith, after the shots, went to Tippit's body. After hanging around there shortly, the two decided to go off in search of the killer (they saw him turn the corner from Tenth onto Patton). When these two reached a point halfway down the block, they looked west in the alley and saw the gunman in the alley (literally in the vicinity where the jacket was found under a car). You see, Bill Smith and Jimmy Burt assumed that the killer fled west through the alley (as opposed to going all the way down to Jefferson) from Patton.
Now, Bill Smith was buddies with Markham's son, James Markham. No doubt Bill Smith told anyone who would listen their fascinating story, including the part about seeing the killer in the alley almost a full block west of Patton (one of them said he was "almost to the next street").
See where I'm going with this? James Markham, hearing his buddy Bill Smith tell his story, undoubtedly would relay the story to his mother, just as I'm sure James would relay his mother's story to Bill Smith. It's perfectly natural.
Anyway, to me, it's obvious that Helen Markham heard (from her son) that the killer was seen in the alley.
However, the witnesses clearly watched the gunman run all the way down Patton and then turn west onto Jefferson.