Brianna Denison vanished with little trace from a friend's home where she was spending the night. Police think the young woman was kidnapped while she slept early Sunday morning.
The FBI has joined the investigation, and detectives are awaiting test results on whether a silver dollar-sized stain on the pillow Denison was using is blood.
Helicopters and police K9 units are aiding search teams.
Denison grew up in Reno and has been attending Santa Barbara City College in California. Family and friends say she was visiting home over the winter break and planned to return to school this week.
