MIAMI -- Prosecutors in Florida found no evidence of a crime in the death of a prison inmate left for nearly two hours in a hot shower, concluding that he died accidentally in part because of undiagnosed heart disease and suffered no burn injuries.

The memo released Friday by the office of Miami-Dade State Attorney Katherine Fernandez Rundle ends a lengthy criminal probe into the 2012 death of 50-year-old Darren Rainey, a mentally troubled man serving a two-year sentence on a cocaine charge.

Milton Grimes, the attorney representing Rainey’s family, disagreed with the conclusion, CBS Miami reports.

“It’s possible that Mr. Rainey fell out in the shower, had a seizure in the shower or a number of things,” said Grimes. “When you combine the heat of the shower and the medication he was on. He should have been under supervision the entire time he was in the shower.”

He also said in a statement that the family is “disappointed and heartbroken” no charges will be brought.

“This is not justice for Darren, for his family, nor for the mentally ill who have been subject to similar abuse and mistreatment,” Grimes said.

The investigation found no evidence that officers at the Dade Correctional Institution regularly used the hot shower to punish or torture inmates, as some of them claimed after Rainey’s death. Assistant State Attorneys Kathleen Hoague and Johnette Hardiman said in the 72-page memo that one inmate’s assertions that Rainey was screaming for help and had been scalded to death were unfounded.

“The evidence fails to show that any correctional officer acted in reckless disregard of Rainey’s life,” they wrote.

Rainey was taken to the shower on June 23, 2012, after he had smeared feces on himself, the walls of his cell and his bedsheets. The shower, which was operated from an adjoining room by a corrections officer to prevent inmates from turning it off, was activated but Rainey refused to stand under the water, according to the memo.

Officer Roland Clarke told Rainey he couldn’t go back to his cell until he washed off. Finally, Rainey said he would comply and asked for soap, which he was given, the memo says.

After starting to wash, Rainey said, “No, I don’t want to do this,” and leaned on a wall away from the water, Clarke told investigators. Officers continued to check on him, and finally after about two hours the decision was made to take Rainey out of the shower, but he was found lying face up in about 3 inches of water with no pulse and not breathing.

One inmate, Harold Hempstead, said he heard Rainey yelling and kicking at the shower door, saying, “I’m sorry. I won’t do it any more” and “I can’t take it no more.”

“And he continued to restate those words and then the kicking started slowing down and then at 9:30 it sounded like he hit the wall and then his body fell,” Hempstead said, according to CBS Miami. “And then there was no more yelling.”

Hempstead, who is credited with sounding the alarm over Rainey’s death, claimed Rainey was brought to a particular shower stall from a different wing of the prison, according to CBS Miami. That wing had its own showers but apparently not like the one Rainey was escorted to the night he died.

The prosecutors found Hempstead’s claims, which he repeated to several news outlets, were not supported by other evidence, including video footage from inside the prison.

“Hempstead’s testimony is inherently unreliable and therefore not credible,” Hoague and Hardiman, the assistant state attorneys, wrote.

“It is apparent to us that in many critical and crucial areas, Hempstead did not seem to have an opportunity to see and know the things about which he testified; he did not seem to have an accurate memory; he has been convicted of a felony, and lastly, his testimony was not consistent with the other testimony and other reliable and undisputed evidence in the case,” the report by Miami-Dade State Attorney’s Office said.

Several witnesses said Rainey’s skin appeared to be peeled back or reddish in some spots -- one inmate claimed he looked like a “boiled lobster” -- but an autopsy found this “slippage” was most likely caused by friction or pressure on his moist and warm skin. This could have happened during efforts to revive him, such as chest compressions, or when officers carried him out of the shower initially, the memo said.

The medical examiner, Emma Lew, attributed Rainey’s death to a combination of his schizophrenia, heart disease and confinement in the small shower space. She said schizophrenic people can have nervous system reactions that trigger a heart attack if they have an underlying condition.

“It is not substantiated that the temperatures inside the shower room were excessively high,” Lew wrote.

According to the State Attorney report, a safety officer of the prison tested the water from the same shower two days after Rainey’s death using a meat thermometer.

“She placed thermometer probe under the running hot water for approximately one minute, and the thermometer read 160 degrees Fahrenheit,” the report states.

Later that same day, she tested the water again and it read 125 degrees Fahrenheit, the report says. According to that same officer, the water was not to exceed 120 degrees Fahrenheit.

Three days after Rainey’s death, the same safety officer sent follow-up emails advising of the temperature readings. She requested work orders and “warned staff not to use that shower,” the report says.

The report also states that nurses who have worked at the prison stated that they never treated an inmate who complained or needed treatment for burns from a hot shower. Also, a majority of inmates told investigators “they had no knowledge about that shower being used to discipline or to torture inmates.”

The prosecutors determined that corrections officers did not commit murder or manslaughter in Rainey’s death and that taking him to the shower was appropriate under the circumstances.

“Placing an inmate who has defecated upon himself in a shower to decontaminate himself is not conduct that is criminally reckless,” they wrote. “There was no evidence of any intent to harm Rainey.”