Korena Roberts, 28, was charged with murder in the death of Heather Snively, 21, also of Tigard, and could face charges in the death of Snively's newborn son, sheriff's Sgt. David Thompson said.
Paramedics called to Roberts' home Friday for a newborn in distress took Roberts and the baby to a hospital thinking she was the mother of the child, CNN reported Sunday.
The baby was pronounced dead at the hospital and authorities returned to the home and found Snively's body in the crawl space beneath the kitchen after doctors said Roberts did not give birth to the child, Thompson said.
Neighbors of Roberts said she told them she was expecting a child, KPTV, Portland, Ore., reported Saturday.
"She didn't appear to be pregnant to us," a neighbor, Doug King, said.