HOUSTON -- Three tipsters to a missing person hotline have claimed that they spotted a missing Rice University student in California, KPRC Local 2 reported Sunday

Matthew Wilson, 21, has not been seen or heard from since December 14.

Wilson's mother is planning to head to Berkley, Calif., on Tuesday to search for her son after the tipsters reported seeing him near the University of California at Berkley.

Wilson's car was recently recovered in the Berkley area. Police found a book inside the car about how to gain a new identity.

Kathy Wilson said Sunday that her son was a quiet and bright student who majored in computer science on a full scholarship at Rice.

Rice University Police have said there are no signs of foul play.

Kathy Wilson said she is worried that her son is depressed and paranoid he will be in trouble for sparking a costly investigation and search and might be too afraid to let anyone know where he is.

"Matthew, you're not in trouble with any police," she said. "They only want you to call me and let me know you're safe."

Matthew Wilson is white, 5 feet 7 inches tall, 135 pounds and has red hair, a full beard, green eyes and wears glasses.

There is a $20,000 reward for information about Matthew Wilson's whereabouts. Anyone with information should contact Rice University police at 713-348-6000.

His family created a Web site to help with the investigation. They blog about any new information released by detectives and how they are holding up.