One summer night in 2005, a worker lowered Mr. Taylor into the tub, turned on the water and left the room. Over the next 15 minutes, the water slowly rose over his head. He drowned before anyone returned.

Joan Taylor, his mother, remembers the words her husband said as dirt was shoveled onto their son's grave.

"This is the last time they're going to dump on you," he told his dead son.

James Taylor's death was no aberration.

In New York, it is unusually common for developmentally disabled people in state care to die for reasons other than natural causes.

One in six of all deaths in state and privately run homes, or more than 1,200 in the past decade, have been attributed to either unnatural or unknown causes, according to data obtained by The New York Times that has never been released.

The figure is more like one in 25 in Connecticut and Massachusetts, which are among the few states that release such data.

What's more, New York has made little effort to track or thoroughly investigate the deaths to look for troubling trends, resulting in the same kinds of errors and preventable deaths, over and over.

The state does not even collect statistics on specific causes of death, leaving many designated as "unknown," sometimes even after a medical examiner has made a ruling.

The Times undertook its own analysis of death records and found disturbing patterns: some residents who were not supposed to be left alone with food choked in bathrooms and kitchens. Others who needed help on stairs tumbled alone to their deaths. Still others ran away again and again until they were found dead.

Mr. Taylor was hardly the only resident to drown in a bathtub. Another developmentally disabled man at a house run by the same nonprofit organization drowned in a tub four months earlier.

Through a Freedom of Information request to the State Commission on Quality of Care and Advocacy for Persons With Disabilities, The Times obtained data for all 7,118 cases of developmentally disabled people - those with conditions like cerebral palsy, autism and Down syndrome - who died while in state care over the past decade.

The data from the agency, which is responsible for overseeing treatment for the developmentally disabled, included only the broad "manner" in which people died - by homicide or suicide, accidents or natural causes.

By far the biggest category, other than natural causes, was "unknown," accounting for 10 percent of all deaths in the system.

The records suggested problems in care may be contributing to those unexplained deaths. The average age of those who died of unknown causes was 40, while the average age of residents dying of natural causes was 54.

The Times reviewed the case files of all the deaths not resulting from natural causes that the commission investigated over the past decade and found there had been concerns about the quality of care in nearly half of the 222 cases.

The records also showed that problems leading to deaths rarely resulted in systemwide steps, like alerts to all operators of homes, to prevent mistakes from recurring. Responses were typically limited to the group home where a resident died.

At homes operated by nonprofit organizations, low-level employees were often fired or disciplined, but repercussions for executives were rare. At state-run homes, it is also difficult to take action against caregivers, who are represented by unions that contest disciplinary measures.

New York relies heavily on the operators of the homes to investigate and determine how a person in their care died and, in a vast majority of cases, accepts that determination. And the state has no uniform training for the nearly 100,000 workers at thousands of state and privately run homes and institutions.

The value of analyzing death records for problems in care that could be prevented through alerts or training has been well established, and is encouraged by the federal Government Accountability Office.Officials in Connecticut, for example, noticed four choking deaths in 2006, the first year the state published such data. They developed a statewide program - two days of initial training and a refresher course every two years thereafter. The state has had just one choking death since 2007. New York has had at least 21 during that same period.