The body of the unidentified woman, in her 70s, was discovered by visiting relatives Monday, who entered her apartment and found her dead, KOAT-TV, Albuquerque, reported Tuesday.
Police said they found an unopened letter near the door with an October 2012 postmark, and said they believe she died at least that long ago. They added she was a hoarder and they had difficulty opening the door.
"This woman looks like a mummy, essentially," Santa Fe police spokeswoman Celina Westervelt said. "All of her skin has dried out. You could see the skeleton underneath. There were no body fluids anymore."
Westervelt said an autopsy would be performed to identify the woman and her cause of death.