CAMP VERDE, Ariz. (AP) – An attorney defending a self-help author on manslaughter charges returned to the possibility that toxins contributed to the deaths of three people following a sweat lodge ceremony shortly after a judge rejected a defense request for acquittal.

Yavapai County Superior Court Judge Warren Darrow ruled Tuesday that James Arthur Ray had a legal duty to check on participants of his 2009 “Spiritual Warrior” seminar, for which they paid $10,000 each to attend.

Darrow also ruled substantial evidence existed that Ray exhibited a reckless state of mind.

Ray's attorneys were seeking a directed verdict of not guilty on manslaughter charges, arguing prosecutors did not prove that Ray was responsible for the deaths of three people stemming from the ceremony. They said Ray had no legal duty to check on participants nor was he aware anyone was dying.

Prosecutors said Ray clearly is guilty. They say he recklessly caused the deaths, conditioned participants to ignore their bodies' signs of danger and failed to render aid to those in distress.

Jurors returned Tuesday afternoon to hear from criminalist Dawn Sy, who tested evidence gathered at the scene. The trial is scheduled through June 21.

Ray led more than 50 people in the ceremony at a retreat he rented just outside Sedona. Sweat lodge ceremonies typically are used by American Indians to rid the body of toxins.

Participants began feeling ill about halfway through the two-hour ceremony in which water is poured on hot rocks, similar to a sauna. At least one person decided not to take part in the sweat lodge and others on the verge of being overcome by the heat left.

Some participants were dragged out unconscious, while others emerged with no major problems. Three people died: Liz Neuman of Prior Lake, Minn.; James Shore of Milwaukee and Kirby Brown of Westtown, N.Y.

The medical examiners who performed autopsies determined that Shore and Brown died of heat stroke and that Neuman died of organ failure. While they stuck to their conclusions on the witness stand, they also testified they could not rule out organophosphates, a chemical typically found in pesticides.

Sy said during questioning by defense attorney Truc Do that her testing of a cross-section of the sweat lodge coverings that included blankets, tarps and rubber turned up trace amounts of a solvent used in plastics. The solvent also can be found in food and beverage products as a flavor enhancer and to make pesticides easier to spray, she said.

Sy said investigators did not ask about the results of that test and another that found volatiles on a log. She said during cross examination by prosecutor Bill Hughes that the results weren't unexpected in those materials.

Sy initially was among nearly 80 witnesses on the prosecution's list, but the state rested its case without calling her. The defense filed its acquittal motion immediately after the last of about three dozen state witnesses testified Friday.

Defense attorney Luis Li argued that participants acknowledged inherent risks during Ray's weeklong seminar through waivers they signed. He said criminal prosecution isn't warranted when consenting adults are placed in peril and not rescued, similar to activities such as bungee jumping and bull riding.

Each of the participants had free will and could have left anytime they wanted, he said.

“Those waivers eliminate any duty of care as provided by black letter law in Arizona and the rest of the country,” he said. “There is no legal duty and if there was, your honor, it was contracted away.”

Yavapai County Attorney Sheila Polk said the waiver is additional evidence that Ray knew his conduct created a risk of death and that it doesn't free him of criminal liability.

She drew comparisons to cases in which children are left in hot cars. If courts can find that defendants in those cases acted recklessly, this jury has enough information and testimony “to find beyond a reasonable doubt that Mr. Ray acted recklessly,” she argued.

Jurors must find that Ray was aware of, and consciously disregarded, a substantial and unjustifiable risk of death to convict him of manslaughter.

Conviction on a lesser charge of negligent homicide would mean that Ray failed to perceive that risk.