PLEASANTON -- A Fremont 15-year-old girl whose absence for more than a week initiated a search was alone at the Stoneridge Mall when police found her Monday night.

Police found the teenager at about 5:45 p.m. in front of the Stoneridge Mall, Pleasanton police Sgt. Jim Knox said. Police received an anonymous phone call that she might be at the mall at 1 Stoneridge Mall Road, Knox said.

The teen was not injured and she was released to her mother, Fremont police spokeswoman Geneva Bosques said Tuesday.

Police believe she was with 30-year-old Ryan Griggs during at least some of her absence.

Griggs has been known to drive a stolen white Ford F150 pickup with a white camper shell, police said. The truck's California license plate is 6E82209.

Police have not said if investigators believe there had been sexual activity between the two. Because it is not known whether she was sexually assaulted, this newspaper is not publishing the teenager's name.

The teen was reported missing on May 5 from her uncle's home in the Irvington district of Fremont. A preliminary investigation showed she left willingly and was not held against her will, Bosques said.

Staff writer Kristin J. Bender contributed to this report. Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH. Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.