In the series, The Big O, how did Negotiator Roger Smith come to control the titular Megadeus robot?

I don’t think this was ever clearly explain just how he got it. This was not an anime adaptation of a manga to my knowledge, so no help there. Given that their entire reality was a simulation, and "The Event" caused most of the city-states populace to have no memories from 40 years prior, this could just be part of the mystery. I was curious if anyone knew anything deeper.