Riley and Dr. Stephen Brigham of New Jersey were taken into custody Wednesday in their respective states. Riley was arrested from her Utah home without incident.
A grand jury indicted to two doctors after a 16-month investigation, according to police.
Maryland is one of 38 states that enforce murder charges if a person is responsible for the death of a viable fetus. Doctors generally consider fetuses to be viable starting around 23 weeks.
A botched 2010 abortion in Elkton, Maryland involved an 18-year-old woman. She was 21 weeks pregnant. The teen suffered a ruptured uterus during the procedure and an injured bowel, according to documents filed in a previous investigation my medical regulators.
Rather than call 911, Riley drove the teen to a nearby hospital, where she and Brigham were uncooperative and Brigham refused to give his name, documents show.
The investigation later revealed a freezer containing 35 late-term fetuses, including one believed to have been aborted at 36 weeks.
Riley remained in the Salt Lake County Jail as of Friday, awaiting an extradition hearing.