The Miami Herald spent a year investigating conditions inside Florida’s assisted-living facilities, the primary homes for the state’s most vulnerable residents: the elderly and mentally ill.

As part of the investigation, reporters examined thousands of inspections carried out by the Florida Agency for Health Care Administration, which is charged with licensing and regulating the state’s 2,850 ALFs.

Reporters traveled across the state visiting a dozen facilities, reviewed thousands of police reports, court cases, medical records, death certificates and government databases, and conducted interviews with dozens of people living and working at the homes, as well as state agents entrusted with investigating the facilities.

In addition, reporters reviewed assisted-living laws in every state and conducted interviews with regulators from six states.

To better understand the inner workings of assisted-living facilities, reporters toured homes and met with administrators and law enforcement officers who respond to emergencies at the facilities.

Though AHCA maintains a website designed to show its inspections, The Miami Herald found many reports were missing, and almost no reports available before 2007.

But by obtaining AHCA databases not readily available to the public, reporters were able to piece together detailed histories of the facilities, identifying the most troubled homes.

In addition, reporters merged other databases, including those of death certificates, emergency response calls, autopsy reports and court records, providing an even fuller picture of breakdowns inside the homes.

Through an automated process, reporters gathered thousands of orders issued by AHCA — including fines, moratoriums, suspensions and revocations — to determine how the agency enforced its mandate to protect residents.

Though AHCA refused to release records of investigations carried out after residents are injured or killed at facilities — known as adverse incident reports — The Miami Herald was able to get a glimpse of some of the events by obtaining key databases from two other agencies.

Confidential documents from the Department of Children & Families and the state Department of Elder Affairs ombudsman program show hundreds of residents were seriously injured in abuse and neglect cases, which included burns, starvation and beatings.

In records never before revealed to the public, the DCF cases include 410 incidents of medical neglect, 281 physical injuries and 912 cases of inadequate supervision.

Beyond the breakdowns in regulation, reporters also examined the role of law enforcement agencies in abuse and neglect cases by interviewing police, prosecutors, funeral directors, medical examiners and forensic nurses.

Though Florida boasts one of the strongest elder-abuse laws in the nation, reporters found that the vast majority of deaths in which the state found abuse and neglect by caregivers did not lead to criminal charges by prosecutors or arrests by police agencies.

Of 70 death investigations carried out by DCF, charges were filed in two, The Miami Herald found.

Both times, the defendants received probation.