SANTA ROSA (CBS SF) -- A body that is believed to be a 15-year-old girl who has been missing since she left for a bike ride April 14 was found Friday night, according to a Santa Rosa police lieutenant.

The father of Charlotte Anna Molinari contacted police around 9 p.m. last Saturday, Sgt. Lisa Banayat said. He said his daughter had left on her bike around 9:45 a.m. that day, possibly bound for Spring Lake.

On Wednesday, detectives located her journal that indicated she was contemplating suicide. They reviewed her Internet history, which revealed she researched directions to Annadel State Park, according to Lt. Steve Bair.

They searched the area Thursday and Friday. Around 5:30 p.m., searchers found the body of a young female in the park.

The case is still under investigation and the Sonoma County coroner's office is scheduled to do a post-mortem examination Monday.

(Copyright 2012 by CBS San Francisco and Bay City News Service. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)