Corpse Girl is an android

“So you’re saying Madelyn’s … what?”
“Maddy Sorensen isn’t real,” said the doctor. “She doesn’t have any life signs because she’s a … a robot. An android. She’s a pile of nanites working together to duplicate the individual parts of a teenage girl on the cellular level, and they don’t realize there’s no actual girl left. They rebuilt a working model of a corpse.”

Excerpt From Ex-Communication, pg 442
Peter Clines
https://books.apple.com/us/book/ex-communication/id635706546