Autopsy is the eighteenth Intel document in Resistance: Fall of Man. It is found in the section level "Angel" in Cheshire, in the second morgue.
...mutations remain unidentifiable as human organs, though redundancies develop. A second heart is common in Hybrids to maintain rapid pulse. Specimen used heat-exchanging device integrated into circulatory system to lower blood temperature and prevent necrosis. Device is common and effective in many Chimera, but decrepitude of so-called "Gray Jacks" indicates a performance envelope.