Three prison officials have been suspended while the state investigates the heat-related death on Wednesday of a woman who had been placed in an outdoor cage for several hours.

A deputy warden, a captain and the lieutenant in charge of supervising the cage at Arizona State Prison Complex-Perryville have been placed on administrative leave. They are now the subject of a criminal investigation by the Arizona Department of Corrections, said Charles L. Ryan, the department's director.

Temperatures reached 107.5 degrees Tuesday in Goodyear, where Marcia Powell collapsed after spending nearly four hours in the sun. Powell, 48, was serving a 27-month sentence for prostitution.

�The death of Marcia Powell is a tragedy and a failure,� Ryan said. �The investigation will determine whether there was negligence and tell us how to remedy our failures.�

In the past year, 79 people have died in department custody. Of those deaths, 70 were determined to be from natural causes. The other deaths included three homicides, three suicides, one drug overdose, and two that are still under investigation.

Powell, who had a history of mental illness, was scheduled to be transferred to a psychiatric unit Tuesday for observation. At 11 a.m., while she waited to be transferred, she was placed in an outdoor, uncovered chain-link holding cell. The cell was in plain view of a staffed control room about 20 yards away.

Although prisoners are given bottled water, department guidelines call for prisoners to be confined outdoors for no more than two hours. Powell had been in the cell for almost twice that long when, at 2:40 p.m., she collapsed.

A half-hour later, Powell was taken to West Valley Hospital. She was taken off life support at 11:15 p.m. and was pronounced dead at 12:42 a.m. Wednesday.

It was unclear Wednesday whether corrections staffers were actively monitoring Powell during her confinement. Ryan said the use of the outdoor holding cells is appropriate as long as prisoners are not kept in them for extended periods of time.

Powell was alone Tuesday when doctors decided to remove her from life support. No family members could be found to be with her in the hospital before she died, and corrections officials said Wednesday that they have still not found a next of kin.

She was believed to have two children, both of whom entered the foster system long ago. Powell herself had several previous felony convictions, records show, including one for drug possession.