The note can be found in Fort Defiance, in a bunkroom on the third floor (cannot be taken).
Belmonte went AWOL for days and came back pleased as a peacock. After Esposito chewed him out, he filed out, grabbed his gear and walked straight through the security door. Everyone was shitting bricks.
The Paladin herself interrogated him for hours. But now Belmonte's bunked up with the Thunder and the rest of us scrubs are parked on our ass out here.
So I cornered Belmonte and asked how the hell he breached security. Only military personnel can get through that, and he was some sort of mechanic Pre-War. Only thing he'd tell me is "Camp McClintock." What the hell? He's such an ass.