Search goes on for missing Calif. teen MORGAN HILL, Calif., March 26 (UPI) -- The search for a missing 15-year-old California girl stretched into its 10th day Monday and her father said he is becoming "desperate for a clue." Sierra LaMar, of Morgan Hill, disappeared the morning of March 16 when she left her home to catch the school bus, NBC's "Today" program reported. Last weekend, about 90 law enforcement officers and several search dogs combed a 12-mile radius near LaMar's mother's home, where she was last seen. So far, the only evidence found have been Sierra's cellphone and her purse, which were found a few miles from her home, authorities said. Police have questioned registered sex offenders in the area. LaMar's father, Steve, is a registered sex offender, but officials have insisted he is not a person of interest in the case. Steve LaMar said Monday he is "desperate right now. I'm desperate for any, any clue.