Theories
Proctor 34

Warning This Section Does Contain Spoilers

Because we know that Vernon is employed at the LFoA facility and would be accessible during the COBRA testing/experiments, and we also know that he is almost doting on Penny, it is reasonable to suggest that he might be Proctor 34 and the one that could not stop himself from initiating contact with Penny during her testing. 

Another possibility is that the Proctor 34 is Sven, but the only reason I discount this is that wouldn't they use his patient number since they use Penny's patient number during the correspondence? John William James' patient number is still used as 1618, so wouldn't Sven be referred to as Proctor 7166?