Well?
Howard Brennan? Harold Weisberg called him "the least credible man in the world." Or Amos Euins? And there were, as I recall, three ear-witnesses on the fifth floor of the TSBD who heard the shots being fired, the working of the bolt and the shells dropping on the floor above them. Of course all this is disputed.
I said witnesses
There is also a video of him standing at the location where he was on 11/22/63 in which he showed the concrete pillar he ducked behind, but I haven't found that one yet.
Euins was recorded by HSCA staff regarding his having Camera with him and his taking photos inside Dealey Plaza on 11/22/63. Strange, but as the years passed by, that Camera has disappeared from the story Euin's is telling.
Euins story in the video is very different from the story he told on the afternoon of the coup d e'tat.No doubt he's found fame by telling people what they want to hear. One startling difference is that on 11 /22/ 63 he did not see a rifle...He said he saw a a " pipe like thing"