The 15-year-old suspect appeared in juvenile court in connection with the Jan. 28 incident. Her name is not being released by KOMO News because she is a juvenile.
She is accused of being one of four people who attacked the 15-year-old victim, punching and kicking her in the head, then stealing her purse, phone and iPod before fleeing from the scene.
All four are charged with first-degree robbery.
The 15-year-old girl charged with being the primary attacker faces up to 2 1/2 years in juvenile detention if convicted. The three other suspects will be charged as adults in King County Superior Court.
The 15-year-old victim told a King County sheriff's detective that the group followed her from a nearby department store into the bus tunnel at Westlake Station on Jan. 28, and she deliberately stood next to the three guards for protection.
The guards didn't intervene, though. They have standing orders to "observe and report," so they called police but did nothing else as the other 15-year-old girl punched and repeatedly kicked the victim in the head.
Government officials as well as executives at Olympic Security Services Inc., which employs the guards, are reviewing that protocol after the guards' response was caught on surveillance video.
"I went to the security and told them that these kids were trying to jump me," the girl said. "I know that I am about to get jumped and I am hanging around the guards to try and get protection. ... I thought the security guards would defend me."
Two Seattle police officers noticed the escalating situation and kicked the group out of the Macy's, then brought the girl and her friend to another exit, the victim said. She reported that she asked the officers for an escort to the bus tunnel, just below the department store, but the officers refused.
The victim, who reported that she lost consciousness during the attack, was not hospitalized. She said she has a potentially fatal heart condition, and tried to protect her chest as she was being kicked.
King County Sheriff's Sgt. John Urquhart said the guards were right to follow their training.
Metro Transit General Manager Kevin Desmond and other King County officials were less forgiving.
"We are very disappointed in what people see in that video," Desmond said. "It was absolutely unacceptable. I know the Olympic Security folks were also disappointed in the response, but again, the employees were following the letter of the agreement."
Metro Transit contracts with the King County Sheriff's Office for 68 police officers, and supplements that force with civilian guards provided by Olympic Security Services Inc. of Tukwila, Wash. All three of the guards involved are Olympic employees.
The guards' duties include helping customers and reporting suspicious objects, disruptive behavior and equipment problems.