The search for a Minnesota mother who fled with her 13-year-old cancer-stricken son to escape court-ordered chemotherapy has turned to Southern California after authorities received a tip. But the officials leading the search that continued Thursday acknowledged that Colleen Hauser and her son, Daniel, could already be in Mexico, possibly to seek treatment for his Hodgkin's lymphoma. Authorities believe the mother and son fled Monday after a court-ordered X-ray showed the tumor in Daniel's chest was growing. Doctors have said the tumor will likely kill Daniel without conventional treatment, but Colleen Hauser favors the natural healing methods of an American Indian religious group known as the Nemenhah Band. Colleen Hauser's husband, the local sheriff and the Nemenhah Band's founder hoped the mother would return home with Daniel. But the pair proved they wouldn't be traced easily. “I just wish we could get to Colleen and tell her to come in,” Brown County Sheriff Rich Hoffmann said. “This is not going to go away. It's a court order.” He said Hauser's husband was cooperating with investigators. Colleen and Daniel Hauser were seen as recently as Tuesday morning in Southern California, and authorities said they believed the two were headed to Mexico. They would only say the pair's location was based on “reliable information.” Hodgkin's lymphoma is a highly curable form of cancer when treated with chemo and radiation. But the teen and his parents rejected chemo after a single treatment, with the boy's mother saying that putting toxic substances in the body violates the family's religious convictions. Hauser said she had been treating the boy's cancer instead with herbal supplements, vitamins, ionized water and other natural alternatives.