Uncle Pete was uncle of Maureen Corley and he owned the Mink Ranch where little Mo grew up. It was a local tourist attraction and put a radio advertisement on KCOR FM to promote his farm, inviting also the kids to look at the minks before they are skinned. Maureen later left the Ranch and joined the Vultures, and the Ranch was abandoned after Pete's death
He only apears on the photograph in the game. Uncle Pete is probably a relative of Maureen's mother, that is, Malcolm Corley's extra-marital lover.