LAS VEGAS >> Las Vegas police said today they have reopened an investigation into the death of a spa worker who was found dead in a cryotherapy chamber.

In addition, the state and the family of 24-year-old Chelsea Patricia Ake-Salvacion, the woman who died, announced their own investigations involving cryotherapy, a treatment for pain and other conditions, and the machine used to subject people to cold temperatures.

Police said the homicide unit would review the case after officers concluded last week that the death was not suspicious and closed the case.

Officer Jesse Roybal said there’s still no immediate evidence of a crime and no new facts have been discovered.

The decision to restart the investigation was prompted by questions from other agencies.

“It’s not a crime. We’re documenting that somebody died,” Roybal said.

The news came on the same day that Nevada regulators announced a review to determine whether businesses that use cryotherapy equipment are protecting clients from possible harm, said Teri Williams, a spokeswoman for the Nevada Division of Industrial Relations.

The increasingly popular but largely unregulated treatment involves subjecting people to brief periods of sub-zero temperatures.

Ake-Salvacion had apparently used a cryotherapy chamber at the Rejuvenice spa where she worked after hours on Oct. 19 and was discovered the next day by a co-worker inside the machine about the size of a phone booth. Albert Ake said his niece was frozen solid.

The U.S. Food and Drug Administration has no oversight responsibility for the treatments. State agencies were initially at a loss to say who might look into the circumstances surrounding the death before the Nevada Division of Industrial Relations announced its investigation.

“Based on developing information … questions about public and workplace safety within this relatively new industry have lingered,” Steve George, administrator of the Division of Industrial Relations, said in a statement.

The state said it is compiling a list of businesses where the machines are used.

Investigators intend to examine equipment, interview employees and managers who operate it, and review published information from regulatory agencies and other sources. The state will also speak to manufacturers and trade and industry groups about the function of the treatment favored by celebrities and sports stars.

The woman’s family through their lawyer, Richard Harris, also announced their own investigation into the cryotherapy chamber made by Poland-based manufacturer Juka. Harris said the machines sell for about $50,000 and are being used across the country.

Juka did not immediately respond to emails seeking comment.

Harris said his personal injury law firm would investigate parts of the Juka machine where Ake-Salvacion was found for possible malfunctions.

He noted its systems are designed to deliver an appropriate amount of nitrogen as part of the chilling process, monitor for healthy oxygen levels, limit the time of each use to three minutes or less, and adjust for the proper height so a user’s head is above the chamber.

“No agency is really responsible in an ongoing way for monitoring, regulating, testing these machines,” Harris said. “And now we see the results.”

Harris suggested that too much nitrogen exposure could have caused Ake-Salvacion to lose consciousness while using the machine. He also said Ake-Salvacion had texted a friend about a possible nitrogen leak in the machine, noting that the nitrogen appeared to be used quickly.

The family and Harris have rejected the notion that she could have made any mistakes that night, insisting that she was an experienced and trained operator.

“Not only can a person freeze to death, you can be overcome by nitrogen,” Harris said. “Too much nitrogen can overwhelm and cause someone to pass out.”

Ake-Salvacion’s cause of death has not yet been determined.

Nevada Occupational Safety and Health investigators have said Ake-Salvacion should not have been using the cryotherapy chamber after hours for personal use, said Williams, the state spokeswoman.

“The facts indicate that the fatality occurred as a result of employee misconduct or non-compliant activity,” Williams said. “The employer cannot be cited … and further investigation is not warranted.”

Attempts to reach the spa’s owners Christian Chateau and Kevin Goujon have been unsuccessful.

Two Rejuvenice locations in Las Vegas and unincorporated Clark County were ordered closed Tuesday after authorities said the operation lacked local business and state cosmetology licenses as well as state-mandated proof of worker compensation insurance.

Rejuvenice has offered 30-minute cryotherapy sessions for about $100, according to online promotions. At least one other cryotherapy center operates in Las Vegas, unrelated to Rejuvenice.