GOLDEN, Colo. -- The trial of a holistic health practitioner charged in the death of a patient got under way Tuesday.

Brian O'Connell, 37, claims to have a doctorate in naturopathy, a form of alternative medicine. He faces 17 criminal charges, including impersonating a physician, illegally practicing medicine and criminally negligent homicide.

O'Connell is the medical director of Mountain Area Naturopathic Associates in Wheat Ridge.

Some experts say he lacks the proper training to be a doctor.

One family said their son died prematurely because of O'Connell's treatments.

David Flanagan said he brought his 19-year-old son, Sean, to O'Connell after they had tried chemotherapy, bone marrow transplants and surgery to help with Sean's cancer.

In December 2003, Sean underwent a procedure called photoluminescence -- also known as ultraviolet blood irradiation. The procedure involves removing blood from the body, passing it under an ultraviolet light and then returning it to the body.

The treatment was supposed to stimulate the immune system by increasing oxygen in the blood but Sean was admitted to a hospital two days later with a bronchial infection. O'Connell then administered the UV light treatment at home, which caused Sean's oxygen saturation levels to drop, David Flanagan said.

Flanagan said that O'Connell then allegedly treated Sean by injecting his blood with hydrogen peroxide. The next day Sean died.

Prosecutors argue that Sean's cause of death was listed as probable complications from the hydrogen peroxide treatment. Flanagan is certain that O'Connell treatment hastened his son's death. His doctor said he had months to live but within two weeks of O'Connell's treatment, he was dead, Flanagan said.

However, other patients stand behind O'connell and his treatments.