SEATTLE - A 15-year-old girl pleaded guilty to a charge of second degree assault for the bus tunnel beating of another teen.
Surveillance video showed the attack as it happened last January.
The video created an uproar because it clearly showed uniformed security guards doing nothing to stop the attack.
The girl was originally charged with first degree robbery, but there was insufficient evidence of intent to commit a robbery.
The girl faces between 15 and 36 weeks in the Department of Juvenile Rehabilitation.
Three adult defendants, Latroy D. Hayman, 20, Domanique L. Whitaker, 18, and Tyrone J. Watson, 18, are each charged with first degree robbery for their alleged involvement in the incident. Their cases are pending trial.
Two other juvenile co-defendants have also pleaded guilty. A 17-year-old boy pleaded guilty in March to fourth degree assault and misdemeanor harassment, and a 17-year-old girl pleaded guilty last month to fourth degree assault. Both were sentenced to 30 days in detention.