In 2012, Nancy meets Gray when she is investigating the murder of Niko Jovic. He is a gruff man, rude and unfriendly, and doesn't like talking. He is disliked by everyone who works at the facility. Nancy learns that Niko hired him.
Eventually, Nancy hears the shredding of documents in his office. Once she lures him away, she has a chance to reassemble one of the documents. It has a clue which leads her to discovering that Gray has a PhD in theoretical physics from Kingston University. He tells her that he was friends with Niko, and that he used to be "the smart one" between them. Niko learned a lot from him., he tells her. Gray studied energy and physics until he had an existential crisis and didn't want to be a part of it anymore. He destroyed the parts of Niko's research on wireless energy that could have potential military applications so that they wouldn't be abused, per an agreement he had with Niko.
After Nancy solves Niko's murder, Gray gets back into the science field and continues Niko's work, opening up some of it to the public.