Hamaseh Kianfar, 30, who befriended 16-year-old Marilyn Webster while working in the guidance center at Alameda County Juvenile Hall, was with the teen when she attacked the 75-year-old woman, authorities said.
While police and prosecutors build their case against Kianfar, a law enforcement source said an Alameda County grand jurycould launch its own investigation into Kianfar's relationship with the teenage suspect and possibly other wards at juvenile hall.
Alameda County officials would not comment on whether they have expanded the scope of their investigation regarding Kianfar's relationship with Webster or others.
Kianfar has been on administrative leave from her job since March 22.
Webster, who was arrested two days after the March 16 attack, is facing charges of attempted murder and assault with a deadly weapon and remains in juvenile hall.
Earlier this week, a judge issued a no-bail arrest warrant for Kianfar, and police later attempted to track her down at her family's San Rafael home. On Wednesday, Kianfar came to the Oakland Police Department's warrant division and surrendered. A judge had lowered her bail to $15,000 standard for the felony count of accessory to attempted murder and Kianfar posted bond.
Her Emeryville attorney, Laurel Headley, declined comment.
For unknown reasons, Kianfar was not booked, fingerprinted or photographed by Oakland police Wednesday, authorities said. She was also given a May 6 court date; Felony suspects are generally required to appear in court within 48 hours.
Why Kianfar surrendered to Oakland police instead of Berkeley police was not known late Wednesday.
Prosecutors charged Kianfar as an "accessory after the fact" because she did not call police or give aid to the bleeding Berkeley woman and then misled police about why she was with the teen, officials said.
Sources said Kianfar originally told police she just happened to be driving by the Berk-
eley Rose Garden when she spotted the teenager.
Later she told police she was visiting friends in North Oakland and afterward spotted Webster looking distraught in downtown Berkeley. Knowing her history, she decided to give her a ride, and they ended up in the Berkeley hills, where the attack occurred.
After the attack, Kianfar spoke to a relative of the teen's but said nothing about the knifing, authorities said.
Two days after the attack, Kianfar told the same relative that Webster had "done something bad" and there was a warrant out for her arrest, authorities said.
It was the relative who took Webster to the Alameda County Sheriff's substation in San Leandro and surrendered her to deputies, authorities said.
Authorities said that when asked about the inconsistencies in her stories, Kianfar said she was confused because she had been traumatized by the incident.
Authorities confirmed that two days before the attack, Webster had climbed out the window of her bedroom at an East Oakland group home and was a runaway when she knifed the Berkeley woman.