It wasn't the COG, it was Niles and his screwed up scientists. Niles was loyal not to Munroe but to a fringe faction in the COG: its in the New Hope collectibles in Gears 5. Munroe shut him down and this rogue faction built him the Mount Kadar Lab. One of the collectibles had Munroe order everyone's arrest. Another (the first collectible upon entering New Hope in Gears 5 in fact) was actually a letter from Sid trying to blow the whistle on Niles' operation. It got intercepted and Sid was fired for it.
In Gears 2 it was HINTED that New Hope was the origin of the Locust or that it had something to do with it at least. Afterall, that message from Niles about Mount Kadar led them to the backdoor to Nexus. Even the books (which are canon and fill in the gaps between the games) don't give a definitive explanation for how the Locust came into being. The closest thing we got was a mention about the Sires in Gears of War: The Slab where the Sires were called early Lambent Humans. Sort of like the Formers but far more mutated and deformed. In any case, I always thought that there was more answers at New Hope than just what they got and I was right.
Honestly, am I the only one that doesn't like how bloodthirsty Richard is in this game. I mean, I know he always had Dick moments, but still he was not that dickish. In the books and comics, it's revealed that Prescott actually has a good heart but was forced to make bad decisions. Maybe it's just so to show him character development that he goes from asshole To last a**** and his death was still very sad, and that Easter Reagan 5, along with 4 everyone else that foul Michael Dom. Tail alice Benjamin anthony adam was so sad I only hope that he was finally at rest and free of the burdens he had And maybe the reason he finally, let's the rest of the cog the truth of the locust Maybe it was because he knew the cog was already in ruins, and he was ready to expose the truth Even though he could have done this years ago, but maybe an earlier assault on nexus would have been suicide.Especially raam alive at that point So it was probably best until later with the destruction of the outer hollows and the death of their general that'll allow them to be vulnerable