(CNN) -- Self-help guru James Ray has been convicted of negligent homicide in the deaths of three participants in an Arizona sweat lodge ceremony, but he was found not guilty of manslaughter charges.
The case will continue June 28, when the jury will convene to make a decision regarding aggravating circumstances in the case.
Prosecutors claimed that Ray's recklessness in operating the sweat lodge caused the deaths of Kirby Brown, 38, of Westtown, New York; James Shore, 40, of Milwaukee; and Lizbeth Marie Neuman, 49, of Prior Lake, Minnesota.
They died after participating in a the ceremony organized and led by Ray in 2009.
At least 15 others who took part in the sweat lodge ceremony became ill. More than 40 others were uninjured.
Prosecutors argued that the lodge, made of willow trees and branches and covered with tarpaulins and blankets, was heated to a perilously high temperature, causing the participants to suffer dehydration and heatstroke. They also said Ray didn't monitor the temperature inside the lodge or the well-being of participants and was indifferent to those clearly having trouble.
Ray's lawyers countered that what happened was a tragic accident, not a crime. They asked witnesses who were in the sweat lodge whether they signed a release form warning them of the dangers. All replied that they signed, but some said they didn't read the form.
Ray's attorneys also suggested that exposure to an unknown toxin in the lodge -- perhaps a pesticide, rat poison or something in the type of wood used to heat the rocks -- could have caused the deaths.
Event participants paid up to $10,000 to seek "new areas of consciousness" at the October 2009 Spiritual Warrior retreat in the desert, according to trial testimony. Many had attended previous James Ray International seminars.