Well, what we know about Randy, Raydon Labs, and Michael's arm so far:
1. In chapter 3 Burt kills a smart zombie on the roof of his shop. This zombie turns out to have a level 3 security badge from Raydon Labs attached to it's belt.
2. CJ had a techie at her tower named Randy, who were sent to the waterworks when the water supplies were low, or something like that. This was told by Sean in chapter 27.
3. Michael broke his arm at the waterworks in chapter 9, and was off screen for about two chapters, untill he arrives at the arena with Saul and Burt.
4. In chapter Michael tells Puck that he was reaching through a doorway, but gets interrupted by Pegs before he can reveal more.
5. While he's asleep at the colony after his arm got fixed by Tanya, he, according to Hope in chapter 19, mentioned a guy named Randy a few times.
6. In chapter 23 Tanya's being dragged away by a zombie with long hair and beard. When Michael shoots at it it turns around, and he recognises him and shouts out the name "Randy".
7. In chapter 35, around the end, Victor spots a zombie with a brown shirt, long hair, and a beard. He's got markings on his face as well. We don't know whether or not this is randy, but to me it seems likely.
8. In chapter 39 Randy's seen on one of the spotters, carrying a bag containing to glass bottles. In the bottles is some kind of liquid with a strong, metalic smell. The letters Fo can be seen on the lable, along with the logo of Raydon Labs. Randy drops this bag when he's jumping the fence at the end of the alley that Michael's chasing him through.

If I've missed anything, just say so... I probably have.