James Shore of Milwaukee and Kirby Brown of Westtown, N.Y. died Thursday night after being overcome in a sweat lodge during a spiritual cleansing ceremony.
Nineteen others were taken to area hospitals, but most were soon released. One remained in critical condition on Saturday.
Yavapai County sheriff Steve Waugh said Saturday that his detectives are focusing on self-help expert and author James Arthur Ray and his staff as they try to determine if criminal negligence played a role in the deaths. No charges have been filed.
The resort is owned by Michael and Amayra Hamilton, who have declined to comment. Ray's spokesman expressed condolences Friday, but wouldn't talk specifically about the deaths. Ray's company, James Ray International, is based in Carlsbad, Calif.
Authorities haven't determined the cause of the deaths and illnesses, but ruled out carbon monoxide poisoning. The incident happened at the Angel Valley Retreat Center just outside scenic Sedona.
Ray rented the facility as part of a five-day "Spiritual Warrior" retreat that promised to "absolutely change your life."
Waugh said the 64 people who were in the crude sweat lodge had fasted for 36 hours, then ate a breakfast buffet on Thursday morning. After various seminars on Thursday, they entered the sweat lodge at about 3 p.m.
A little more than two hours later, Shore and Brown were taken out of the lodge without a pulse and not breathing. By the time rescue crews reached the remote property, other people also were experiencing medical distress.
A nurse hired by Ray was directing rescue efforts including CPR when emergency crews arrived, Waugh said. Shore and Brown were pronounced dead when they arrived at a hospital.
An autopsy was conducted on Friday, but the results are pending additional tests.
The 19 others who were taken to hospitals suffered from various ailments, including respiratory arrest, kidney failure or elevated body temperature.
By Associated Press Writer Felicia Fonseca