Agent Keller was hired shortly after Orpheus Group's first management restructuring. He was trained apart from other Agents, ostensibly as part of a new anti-spectre tactics program developed by the new Board of Directors who came into power along with Tad Eccles.
During the recent counter-coup against Eccles' management, it was revealed that Keller had learned to somehow transform into a spectre, or at least assume its outer appearance. Keller was killed during a fight with Agents loyal to Kate Hennisson and the original Board of Directors.