Judge Michael N. Annis accepted Barnard's negotiated plea and imposed a prison term of two consecutive life sentences plus 10 years.
Barnard, 22, pleaded guilty in Richmond County Superior Court to murder, aggravated assault, two counts of armed robbery and two weapon violations in the March 28, 2007, slaying of Eladio Gonzales, 23, and the wounding of Jose Mochica.
Barnard picked up the two men at a North Augusta apartment complex and drove them to a remote area off Brickyard Pond Road, District Attorney Ashley Wright told the judge Wednesday.
Waiting with a shotgun stolen from Barnard's mother were Antonio Jones and Ronald Banks. Jones shot both men repeatedly with the 12-gauge shotgun, and then Barnard and her cohorts picked through the victims' pockets, Wright said.
Instead of wads of cash and jewelry they thought the men would have, they found $58 and two sets of keys and cell phones.
Barnard, who had just turned 18 at the time, dropped out of high school in the 10th grade. She has been in the Richmond County jail since her arrest a day after the crimes.
Jones, 32, pleaded guilty to all charges in October 2009. He was sentenced to life in prison without possibility of parole. Annis also imposed the mandatory additional sentence of five years for a weapons charge.
Banks, who had a criminal history dating back two decades, was 55 when he died of natural causes while awaiting trial in March 2008.
Barnard told investigators that she knew Jones from the neighborhood where she grew up, according to previous court testimony. A couple of weeks before the killings, they started hanging out together. At the time, Jones was living with Banks.
Barnard had intended to target another Hispanic man she knew, but she happened to cross the path of Gonzalez and Mochica the night the robbery was planned. She told investigators she was acquainted with Gonzalez.
Both men were from Mexico, where Mochica has since returned. He recovered from gunshot wounds to the back of his head, back and leg, but still has the scars, Wright said.
Mochica, 30, didn't attend Wednesday's hearing, but he was in agreement with Barnard's plea and sentence, Wright said.