MIAMI (Reuters) - A dozen Florida nursing home patients who died from sweltering heat during a 2017 post-hurricane power outage were victims of neglect by four caregivers jailed this week to face manslaughter charges, and more arrests are expected, police said on Tuesday.

The former manager and three nurses who worked at the now-closed Rehabilitation Center at Hollywood Hills, north of Miami, “failed to protect their patients and render aid when it was needed most,” Hollywood Police Chief Chris O’Brien told a news conference, detailing the two-year investigation.

Defense lawyers say their clients were innocent of criminal wrongdoing and did their best to care for the victims, all of them in frail health, under difficult, unpredictable circumstances posed by one of the most powerful Atlantic storms on record.

The 12 victims, ranging in age from 57 to 99, were found to have died from heat exposure after being left with little or no air conditioning in the nursing home for days after Hurricane Irma knocked out power to the cooling system on Sept. 10, 2017. More than 80 deaths were attributed to the storm in the Caribbean and U.S. mainland.

State regulators suspended the nursing home’s license soon after, and the facility was closed. Two months later, the Broward County coroner ruled the deaths homicides resulting from heat exposure.

Two of the former employees, Jorge Carballo, 61, the facility’s administrator, and Sergo Colin, 45, a supervising nurse, were each booked on suspicion of 12 counts of aggravated manslaughter. Althia Meggie, 36, a registered nurse, faced two counts of manslaughter and two counts of evidence tampering.

After surrendering to authorities at the Broward County Jail in nearby Fort Lauderdale on Monday, the three defendants posted bond on Tuesday - $17,000 for Meggie and $90,000 each for Carballo and Colin, defense lawyer David Frankel said.

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COVER-UP ATTEMPT SUSPECTED

A fourth defendant, Tamika Miller, 31, a licensed practical nurse, was booked on six counts of aggravated manslaughter and three counts of evidence tampering. She was arrested in Miami on Saturday and was being held in the Miami-Dade County jail, pending extradition to Broward County.

Hollywood Police Major Steven Bolger, head of the department’s criminal investigations, said the altering of medical records after the incident “clearly demonstrates some kind of attempt to cover something up.”

“We do anticipate additional arrests,” Bolger added.

Most of the dead were under hospice care and moving them to another facility would have proven medically risky, Frankel said. The nursing home repeatedly sought to get its power restored in the immediate aftermath of the storm, to no avail, he said.

City officials said the rehab center continued to operate without central air conditioning as daytime temperatures outside rose to 90 degrees Fahrenheit (32 degrees Celsius). Portable air coolers and fans were placed throughout the building but were ineffective in curtailing the heat, authorities said.

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“They didn’t do enough,” O’Brien said. “These are trained professionals that should’ve been aware of the hazards taking place and they chose to ignore them.”

An evacuation described by medical workers as chaotic was finally carried out on the third day after the storm, as residents in the overheated building began lapsing into cardiac arrest. More than 140 patients there ended up being moved to a hospital across the street.

Pedro Franco, who lost his father, Miguel Franco, 93, and mother, Celilia Franco, 92, called the arrests of the four employees “step one.”

“We’ve got to go all the way to the end until we see that these people have been convicted of the crimes that they committed,” he told WSVN-TV in Miami.