Jimmy Burt and Frank Cimino are two other witnesses at the scene who were not called by the WC. They have something else in common with Bowley: they said they showed up too late to see either the shooting or the escaping perp. It wouldn't be surprising that they wouldn't be called to testify to a crime that they did not actually witness.
They called Callaway, Guinyard and Reynolds, who didn't actually witness a crime and only saw a man running down the street and they had no way of knowing who he was. Besides, it was Bowley who called the dispatcher and helped Callaway to put Tippit in the ambulance. He would have been a far more valuable witness that Burt and Cimino.
BTW, in 1963, people's lives ran to the pulse of mechanical and electromechanical timepieces that were set using other mechanical clocks as a reference. A few nerdy types might periodically dial into the National Bureau of Standards' time broadcast on shortwave and sync to that, but very few made that level of effort. As such, any randomly-selected timepiece would commonly be expected to be as much as five minutes off of some reference time; any two clocks could be off by as much as ten minutes. This expected discrepancy was the basis for the old advice to always try to be ten minutes early to any appointment. You never knew when your watch was five minutes slow and the other guy's was five minutes fast. And it explains why the timing arguments regarding the Tippit shooting tend to be an asinine waste of everyone's time.
You never knew when your watch was five minutes slow and the other guy's was five minutes fast. Really? And what about if it meant missing your daily bus to work or being late for picking up your daughter from school?
Besides, individual time estimates are not even the issue here. The time line I have presented earlier is a combination and sequence of events that all relate to and corroborate eachother.
1. Markham arriving at 10th street and seeing Tippit get killed
2. Bowley arriving at 10th street just after Tippit was killed and working the radio
3. Callaway arriving at 10th street and seeing Bowley working the radio
4. Callaway and Bowley helping to put Tippit in the ambulance
5. Tippit being declared DOA at Methodist Hospital at 1.15
6. Detective Davenport confirming the DOA at 1.15
Markham said she left home just after 1pm. She only needed to walk one block to get to 10th street. Her own estimate was 1.06. Allow two minutes for the one block walk and you get her to 10th street at 1.08. She sees Tippit get shot.
Bowley said in his affidavit that when he arrived at the crime scene he saw the officer lying in the street and looked at his watch, which said 1.10. That is corroboration that Markham was indeed at 10th street prior to 1.10. .... and so on.
When you move Markham's timeline, you also need to move all others and that's what you can't do. All you can do is dismiss it out of hand, which is what LNs always do when confronted with evidence they can't explain. Rather than dealing with the entire time line honestly, it's far easier for the LNs to simply dismiss it all because time estimates are not 100% reliable.
It's ironic though that those same LNs place the timing of Tippit's murder at 1.14 or 1.15 solely based upon times mentioned in the transcripts of the DPD radio, when the man in charge of those dispatchers is on record to the HSCA saying that the times given on the recordings/transcripts are "police time" and not real time.