Brennan was an important witness as he claimed to see a variety of events. It is important to establish with some accuracy when he took up position.
From Brennan's WC testimony.....
Brennan take up position on the wall about 12.24pm
Mr. BELIN. Mr. Brennan, where were you on the early part of the afternoon of November 22, 1963, say around noon or so?
Mr. BRENNAN. I left a position behind the Book Store, which is a leased part of Katy Yards, which we have fabrication for pipe for the Republic Bank Building. At 12 o'clock I went to the cafeteria on the corner of Main and Record. I believe that is it.
Mr. BELIN. That would be at Main and Record Streets in Dallas?
Mr. BRENNAN. Yes.
Mr. BELIN. And did you have your lunch there?
Mr. BRENNAN. Yes.
Mr. BELIN. And then after lunch, where did you go?
Mr. BRENNAN. I finished lunch and I glanced at a clock--I don't know exactly where the clock is located--and noticed it was 12:18. So I thought I still had a few minutes, that I might see the parade and the President. I walked to the corner of Houston and Elm.
Mr. BELIN. What route did you take to get to Houston and Elm?
Mr. BRENNAN. I went west on Main.
Mr. BELIN. You went west on Main from Record Street to--
Mr. BRENNAN. Houston.
Mr. BELIN. Houston
Mr. BRENNAN. And on the east side of Houston, I walked to Elm.
Mr. BELIN. All right.
Mr. BRENNAN. Crossed the street to the southwest corner of Houston and Elm.
Mr. BELIN. Do you have any estimate about how long it took you to get there?
Mr. BRENNAN. A possibility I would say more or less 4 minutes.
Mr. BELIN. And then what did you do when you got to the southwest corner of Houston and Elm?
Mr. BRENNAN. I stayed around a couple of minutes. There was a man having an epileptic fit, a possibility of 20 yards east--south of this corner. And they were being attended by some civilians and officers, and I believe an ambulance picked him up.
Mr. BELIN. All right.
Mr. BRENNAN. And I walked over to this retainer wall of this little park pool and jumped up on the top ledge.
Seems pretty clear......leaves cafeteria at 12.18, walks for 4 minutes, watches Belknap having fit and attended by officers and ambulance for couple of minutes.
12.18+4+2=12.24pm
As confirmation the ambulance left Dealy Plaza just before 12.25pm according to the transcripts.
Therefore all of Brennan's relevant observations occur after this time.
The defence rests.....If you disagree with this analysis.....go for it.