Last remained jailed in lieu of $500,000 bail with arraignment scheduled Friday. She faces up to life in prison if convicted.
Last's attorney, Suzanne Hayden of the Clallam County public defender's office, did not immediately return a phone call Wednesday.
The baby's body was found Monday by authorities combing 60 tons of trash at a dump site near Tacoma.
An affidavit filed that day said Last "put her baby face down into a toilet and allowed it to drown for several minutes until it died. Then she threw her son into the trash can outside in a plastic garbage bag."
Port Angeles police Chief Terry Gallagher had said that DNA testing to confirm the infant's parentage might not be available for a month or more.
Prosecutors said Last's father, Ronald Last Jr., 41, was charged Monday with possession of a firearm and possession of methamphetamine, both felonies, and with concealing a birth, a gross misdemeanor. He remained in the Clallam County jail.
Investigators in Port Angeles, about 65 miles northwest of Seattle, believe the baby boy died after being born to the girl on or about Dec. 31, and then was put in the trash.
