She created a "sanitarium", Wilderness Heights, in Olalla, Washington, where inpatients fasted for days, weeks or months, on a diet of small amounts of tomato and asparagus juice and occasionally, a small teaspoon of orange juice. While some patients survived and publicly sang her praises, more than 40 patients died under her care, most from starvation.

In 1912 she was convicted of manslaughter for the death of Claire Williamson, a wealthy British woman, who weighed less than 50 pounds at the time of her death. At the trial it was proved that Hazzard had forged Williamson's will and stolen most of her valuables.