I think the statements of W-11 and W-20, putting the start of the altercation north of their unit, are strongly supported by the pattern of what was and wasn't heard by different witnesses.
W-11 and W-18 distinguished the sounds of two or more men shouting, before the screams for help began. None of the witnesses south of W-11's unit heard that.
W-3, W-6, and W-14 only heard the screams for help. W-1 heard a noise like screaming kids, either 'no' or wordless (3/1,
heard one or two words, like 'no' or 'yo', shortly before the shot (3/1, 0:48-55, 3/9, 2:36-3:04, 3/20, 7:42-57).
Because of the timing, I don't think the 'yo' suggested by W-2 should be identified with the 'yo' that Zimmerman attributed to Martin once, in the reenactment
Another piece of the mosaic is W-6's description of noise that at first seemed distant and then came closer.W-6, FDLE, 3/20
W-6: And, while we were watching TV, we kinda heard, some loud noise outside. So we figured maybe it was just, you know, either kids in the neighborhood, or people, you know, just, having a good time outside. And, then we heard it again, so we muted the TV but didn't hear anything for a second. And then we heard it, like it was coming towards us, getting a little louder.
W-6: You could tell it was farther away from where it ended up, in the grass area, you know, behind our townhomes right here. It seemed like it was a lot farther away, because, as time went on, it got closer, and you could, could really, tell, "Oh, that's, I think that's someone really yelling help this time," and it's not, people outside, you know, roughhousing, and, you know.
W-6: If you hear someone yelling, and they're two blocks, three blocks down, it's gonna be a faint sound, you know, you're not gonna hear it as loud. But it sounded like it more, it more, it progressed towards us. I don't know if it was coming from the left or the right. But, the sound just got louder, because I think it, either someone had started, you know, yelling "Help!", and it just got closer and closer, until, you know, we could truly hear it, close enough, and that makes sense because it was right, you know, in the back yard area. That's what I mean, it sounded, you know, like it was getting closer, just the, the sound of the "Help"s, that were getting closer, with movement towards, you know, our location.
The last pieces are the items found on the ground.
The keychain flashlight, found a few feet to the south and west of the T, was turned on, suggesting that it was dropped from someone's hand.
In his FDLE interview, W-13 indicated he saw the keychain flashlight on the ground near the T, just after he went outside.
Investigator: Did you, after you went outside with your flashlight, and looked around, was it anything laying on the ground that you noticed out of the ordinary?
W-13: No. Along, along with just the kid laying there, I saw, I noticed there was one, it, it looked like one of those tactical flashlights. And then, towards the corner, on the sidewalk, across from where the, that poop station is, was a, like a little flashlight. I don't know if it could have been, like, it looked like a flashlight to me anyways. So it looked like there was two flashlights on the ground.
The only place I know to find this interview is Axiom Amnesia, which I've been asked not to link.
Zimmerman's main flashlight, and Martin's phone, were probably in their pockets, and worked their way out as the two wrestled. That would take time, consistent with their locations close to where the struggle ended.