Skin-stealers ingest scraps of skin from corpses, typically removed from the chest above the heart. This, along with some catalyzing component, allows them to wear the victim's skin as their own for a prolonged period.
It seems the ingested skin provides limited memories from the victim, which allows for such thorough infiltration. A few skin-stealers have slipped up and given themselves away, but we have no idea how many are in our ranks.
This book was taken from The Elder Scrolls series of video games or from websites created and owned by ZeniMax Online Studios, the copyright of which is held by ZeniMax Online Studios. All trademarks and registered trademarks present in the image are proprietary to ZeniMax Online Studios, the inclusion of which implies no affiliation with The Elder Scrolls Wiki. The use of such images is believed to fall under the fair use doctrine of copyright law.