Camp Verde, Arizona (CNN) -- Opening statements began Tuesday in the trial of self-help author and speaker James Arthur Ray, who is charged with three counts of reckless manslaughter in the death of three people at an Arizona sweat lodge.
The trial stems from a well-publicized incident that took place during a ceremony at a five-day retreat in Sedona, Arizona, on October 8, 2009. Two people died during the ceremony at Angel Valley Retreat Center. A third died nine days later, and -- authorities allege -- at least 15 others fell ill.
Ray could face up to 10 years in prison on each count if convicted. His attorney argued the author is not to blame for the deaths.
"I'm here to say that they died as the result of an accident -- a tragic accident -- not a crime," defense attorney Luis Li said during his opening statement.
"We do not seek to minimize the tragedy of the sweat lodge deaths," read a December 2009 letter to prosecutors from Li. "But these deaths were not the result of criminal conduct. Mr. Ray and his team relied on Angel Valley to provide a safe environment, warned people of the risks, did not force people to participate, did not prevent them from leaving, and did everything they could to prepare for any problems and to assist when problems arose."
Prosecutors claim Ray, 53, was reckless and 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 heat stroke.
Kirby Brown, 38, of Westtown, New York, and James Shore, 40, of Milwaukee, died on October 8. Lizbeth Marie Neuman, 49, of Prior Lake, Minnesota, died on October 17.
"Three vibrant, healthy adults ... entered a sweat lodge at a retreat center in Sedona," prosecutor Sheila Polk said during her opening statement. "Each one was eager to gain knowledge and each was looking for wisdom and personal insight. Instead of growth and enlightenment, Kirby, James and Liz found death."
On Tuesday, Ray appeared in court dressed in a dark suit and blue shirt. He sat calmly, appearing engaged, as the judge spoke and stared straight ahead as the lawyers made their statements.
The sweat lodge ceremony consisted of eight rounds, with each round lasting 10 to 15 minutes. While they were not prevented from leaving, participants have said they were encouraged to wait until the breaks between rounds.
Ray encouraged participants to hydrate throughout the retreat and warned them the sweat lodge would be very hot, his attorney has said. Participants signed a release form saying that the retreat activities could include a sweat lodge with enclosed spaces and high temperatures, Li said.
In interviews with authorities, some participants recounted feeling distress in the first few rounds. Later, they told police, people began to pass out, others began to vomit and still others went into shock. Some were encouraged to lie down in the dirt to seek relief from the heat.
"(Ray) knew that people were in trouble," Tom McFeeley, Brown's cousin, told HLN's Jane Velez-Mitchell on Monday. "Those calls for help were ignored."
Ray had conducted the Spiritual Warrior Retreat for six years at a cost of about $10,000 to participants. The sweat lodge, 5 feet tall and 23 feet wide, was built to accommodate up to 75 people. There was a pit in the center where heated rocks were placed. Ray poured water over them to create steam.
Prosecutors maintain that Ray psychologically pressured participants to remain in the lodge even when they weren't feeling well, contributing to their deaths.
Defense attorneys dispute that.
Li wrote in the 2009 letter that Ray "did not lead or pressure participants into making a choice they otherwise would not have made. This was a five-day retreat, not a cult. The JRI (James Ray International, Ray's company) philosophy is a practical approach to creating a successful life, not a religious practice."
The trial is expected to last some four months.
Beth Karas is a correspondent for "In Session," which airs weekdays 9 a.m. to 3 p.m. ET on CNN's sister network, truTV.