Quaneysha Greeley, 19, was returned to Maine from New York Thursday.
She was ordered to be held without bail following a court hearing Friday afternoon in Machias.
Greeley and Carine Reeves, 37, are accused of killing Sally Shaw last month and leaving her on the side of a road in Cherryfield.
Police said they fled to New York, but were arrested a week later.
Authorities haven't speculated on a motive for the alleged crime and they haven't said how Shaw was killed. Court documents have been impounded.
Both Greeley and Reeves announced they planned to fight the extradition process, but Greeley returned last night and will appear in court again next week for a bail hearing.
Reeves is still being held in New York on unrelated charges in that state.