NEW ULM, Minn. — Authorities nationwide are on the lookout for a mother and her 13-year-old son who have been refusing the chemotherapy that doctors say could save the boy's life.

Colleen Hauser and her son, Daniel, who has Hodgkin's lymphoma, apparently left their southern Minnesota home sometime after a Monday doctor's appointment and X-ray showed his tumor had grown.

Brown County District Judge John Rodenberg issued an arrest warrant Tuesday for Colleen Hauser and ruled her in contempt of court. Rodenberg also ordered that Daniel be placed in foster care and immediately evaluated by a cancer specialist for treatment.

The boy's father, Anthony Hauser, testified he didn't know where his wife and son were but has made no attempt to find them. He testified he last saw his son Monday morning, and he saw his wife only briefly that evening when she said she was leaving "for a time."

Officials distributed the arrest warrant nationwide and issued a crime alert to businesses around the country, Brown County Sheriff Rich Hoffman said. He said investigators were following some leads locally, but declined to elaborate.

"It's absolutely crazy. It's very disappointing," James Olson, the attorney representing Brown County Family Services. "We're trying to do what's right for this young man."

Daniel's Hodgkin's lymphoma is considered highly curable with chemotherapy and radiation, but the boy quit chemo after a single treatment. With his parents, he opted instead for "alternative medicines," citing religious beliefs. That led authorities to seek custody. Rodenberg last week ruled that Daniel's parents were medically neglecting their son.

The Hausers are Roman Catholic and also believe in the "do no harm" philosophy of the Nemenhah Band, a Missouri-based religious group that believes in natural healing methods advocated by some American Indians.

Colleen Hauser testified earlier that she had been treating his cancer with herbal supplements, vitamins, ionized water and other natural alternatives.

The founder of Nemenhah, Philip Cloudpiler Landis, said it was a bad idea for Colleen Hauser to flee with her son.

"She should have gone to court," Landis said. "It's how we work these things out. You don't solve anything by disregarding the order of the judge."

And Anthony Hauser now agrees that Daniel needs to be taken back to a doctor for re-evaluation for the best treatment, said Calvin Johnson, an attorney for the parents.

The family was due in court Tuesday to report the results of a chest X-ray and their arrangements for an oncologist. But only Daniel's father appeared. He told Rodenberg he last saw his wife Monday evening.

"She said she was going to leave," Hauser testified. "She said, 'That's all you need to know.' And that's all I know."

He said Colleen Hauser left her cell phone at their home in Sleepy Eye.

The family's doctor, James Joyce, testified by telephone that he examined Daniel on Monday, and an X-ray showed his tumor had grown to the size it was when he was first diagnosed.

"He had basically gotten back all the trouble he had in January," the doctor said.

He said Daniel was at risk of substantial physical harm and needed immediate action.

Daniel was accompanied to the appointment by his mother and Susan Daya, a California attorney.

Joyce testified that he offered to make appointments for Daniel with oncologists, but the Hausers declined. He also said he tried to give Daniel more information about lymphoma but that the three left in a rush.

In his ruling last week, Rodenberg wrote that he would not order chemotherapy if Daniel's prognosis was poor. But if the outlook was good, it appeared chemotherapy and possibly radiation would be in the boy's best interest, he wrote.

Daniel's lymphoma was diagnosed in January, and six rounds of chemotherapy were recommended. He and his parents sought other opinions, but the doctors agreed with the initial assessment.

State statutes require parents to provide necessary medical care for a child, Rodenberg wrote. The statutes say alternative and complementary health care methods aren't enough.