Nothing, it seemed, was unusual about Joseph Shepter's death.

A retired U.S. government scientist, Shepter spent his final two years dwelling in a nursing home in Mountain Mesa, Calif., a small town northeast of Bakersfield. A stroke had paralyzed much of his body, while dementia had eroded his ability to communicate.

He died in January 2007 at age 76. On Shepter's death certificate, Dr. Hoshang Pormir, the nursing home's chief medical officer, explained that the cause was heart failure brought on by clogged arteries.

Shepter's family had no reason to doubt it. The local coroner never looked into the death. Shepter's body was interred in a local cemetery.

But a tip from a nursing-home staffer would later prompt state officials to re-examine the case and reach a very different conclusion.

When investigators reviewed Shepter's medical records, they determined that he had actually died of a combination of ailments often related to poor care, including an infected ulcer, pneumonia, dehydration and sepsis.

Investigators also concluded that Shepter's demise was hastened by the inappropriate administration of powerful antipsychotic drugs, which can have potentially lethal side effects for seniors.

Prosecutors in 2009 charged Pormir and two former colleagues with killing Shepter and two other elderly residents. They've pleaded not guilty. The criminal case is ongoing.

Health-care regulators have already taken action, severely restricting the doctor's medical license. The federal government has fined the home nearly $150,000.

Shepter's story illustrates a problem that extends far beyond a single California nursing home. ProPublica and PBS "Frontline" have identified more than three-dozen cases in which the alleged neglect, abuse or even murder of seniors eluded authorities. But for the intervention of whistleblowers, concerned relatives and others, the truth about these deaths might never have come to light.

For more than a year, ProPublica, in concert with other news organizations, has scrutinized the nation's coroner and medical examiner offices, which are responsible for probing sudden and unusual fatalities. We found that these agencies -- hampered by chronic underfunding, a shortage of trained doctors and a lack of national standards -- have sometimes helped to send innocent people to prison and allowed killers to walk free.

When it comes to the elderly, the system errs by omission. If a senior like Shepter dies under suspicious circumstances, there's no guarantee anyone will ever investigate. Catherine Hawes, a Texas A&M health-policy researcher who has studied elder abuse for the U.S. Department of Justice, described the issue as "a hidden national scandal."

Because of gaps in government data, it's impossible to say how many suspicious cases have been written off as natural fatalities. However, the limited evidence available points to a significant problem: When investigators in one jurisdiction comprehensively reviewed deaths of older people, they discovered scores of cases in which elders suffered mistreatment.

An array of systemic flaws has led to case after case being overlooked:

When treating physicians report that a death is natural, coroners and medical examiners almost never investigate. But doctors often get it wrong. In one 2008 study, nearly half the doctors surveyed failed to identify the correct cause of death for an elderly patient with a brain injury caused by a fall.

In most states, doctors can fill out a death certificate without ever seeing the body. That explains how a Pennsylvania physician said her 83-year-old patient had died of natural causes when, in fact, he'd been beaten to death by an aide. The doctor never saw the 16-inch bruise that covered the man's left side.

Autopsies of seniors have become increasingly rare even as the population age 65 or older has grown. Between 1972 and 2007, a government analysis found, the share of U.S. autopsies performed on seniors dropped from 37 percent to 17 percent.

Dr. Michael Dobersen, a forensic pathologist and the coroner for Arapahoe County, Colo., said he worries about suspicious deaths in nursing homes. "Sometimes, if I don't want to sleep at night, I think about all the cases that we miss," Dobersen said. "I'm afraid we're not looking very hard."

With the graying of the baby boom generation, such concerns will only grow in urgency. Within a few years, nearly one-third of all Americans will be over 60.

In a handful of locales, coroners and medical examiners have begun to view older Americans as a vulnerable population whose deaths require extra attention. Some counties have formed elder death review teams that bring special expertise to cases of possible abuse or neglect. In Arkansas, thanks to one crusading coroner, state law requires the review of all nursing-home fatalities, including those blamed on natural causes.

But those efforts are the exception. In most places, little is being done to ensure that suspicious senior deaths are being investigated.

"We're where child abuse was 30 years ago," said Dr. Kathryn Locatell, a geriatrician who specializes in diagnosing elder abuse. "I think it's ageism -- I think it boils down to that one word. We don't value old people. We don't want to think about ourselves getting old."

Checking the Wrong Box

There were two reasons that Joseph Shepter's passing initially triggered no scrutiny from authorities. He was in a doctor's care. And his physician classified the death as natural.

Across the country, state laws rely on doctors to separate extraordinary fatalities from routine ones, principally by what they record on death certificates.

When a doctor encounters an unusual fatality -- a death that may have been caused by homicide or suicide or accident -- the physician must report it to the coroner or medical examiner for further investigation. The investigative work can be as minimal as gathering clues from the place where a body was found, or as extensive as a full autopsy -- the dissection and evaluation of a corpse to pinpoint the precise reason for death.

In Shepter's case, Pormir, the nursing-home doctor, checked off a small box on the death certificate indicating that he never contacted the county coroner. There was no autopsy.

The laws assume physicians like Pormir will report deaths accurately and fully, flagging suspicious cases.

In reality, though, death certificates are frequently erroneous or incomplete, academic research has shown. A study published last year in The American Journal of Forensic Medicine and Pathology found that nearly half of 371 Florida death certificates surveyed had errors in them.

Doctors without training in forensics often have trouble determining which cases should be referred to a coroner or medical examiner.

In a 2008 study, 225 physicians were asked to determine what killed an elderly man who had fallen and suffered a severe head injury. Just over half of the doctors correctly identified bleeding of the brain as the primary cause of death. Nearly two-thirds didn't list the fall as a contributing factor.

"I knew people were going to get it wrong, but it was a surprise just how poorly people did," said Dr. Marian Betz, who led the study and teaches medicine at the University of Colorado.

Robert Anderson, chief of mortality statistics for the Centers for Disease Control and Prevention, said some doctors don't grasp the significance of death certificates.

"I've had instances where the physician just doesn't understand the importance of what they're writing down," said Anderson, who trains doctors in how to certify deaths. "I'm appalled when I hear that."

State officials in Washington and Maryland routinely check the veracity of death certificates, but most states rarely do so, Anderson said.

In Seattle, Dr. Richard Harruff has gone a step further. As the chief medical examiner for King County, Harruff launched a program in 2008 to double-check fatalities listed as natural on county death certificates. By 2010, the program had caught 347 serious misdiagnoses. Two cases were actually homicides. Two were suicides. More than 100 were accidental deaths due to falls or choking.

"If we want ensure that all death certificates are accurate, there has to be a professional, independent review process," said Harruff.

In Shepter's case, the death certificate deflected any investigation until an employee came forward with concerns about conditions at the nursing home, a public, 74-bed facility run by the Kern Valley Healthcare District.

The same month that Shepter died, a nurse told state officials that staffers were using potent antipsychotic drugs to "chemically restrain" residents with dementia, which can cause unruly and erratic behavior. Her complaint prompted the California Department of Public Health to cite the nursing home for unnecessarily doping 23 seniors and led to the federal fine.

It also spurred the California attorney general's office to open a criminal inquiry. Prosecutors asked Locatell, the elder abuse specialist, to evaluate the medical files of the nursing home's residents, including Shepter.

"I saw all kinds of indicators of neglect," said Locatell, noting that Shepter had lost almost 20 percent of his body weight over the span of three months. She said she was shocked by the "callousness of the staff towards this man."

In early 2009, prosecutors charged Pormir and two former co-workers with elder abuse that led to the deaths of Shepter and two additional residents, and with mistreating five others.

Kern Valley Healthcare District chief executive Timothy McGlew said he could not comment on the case except to say that his staff is cooperating with investigators.

The case has not yet gone to trial. Pormir and his co-defendants declined to comment.

For Shepter's son, the charges of criminal elder abuse came as a terrible surprise.

"I had no idea anything was wrong," said Joseph Shepter III, who goes by Joe. He and his sister have filed a civil lawsuit in Kern County Superior Court against the nursing home, Pormir and other staffers, alleging that they committed elder abuse and violated Shepter's rights. Pormir and the others have denied the allegations, court records show.

Joe Shepter used to think that his father "died a somewhat peaceful death" surrounded by caring professionals. Instead, he now believes, his "father was lying in a hospital bed essentially dying of thirst, unable to express himself -- so people could have a nice, quiet cup of tea."

Signing Off Without Seeing the Body

In many states, laws are so lax that doctors can sign off on death certificates without having seen a patient in months or actually viewing the body. As a result, even obvious signs of abuse have gone unnoticed by authorities in some instances.

Take the case of William Neff, a diminutive 83-year-old who passed away in an assisted-living facility in Bucks County, Pa. A World War II veteran, Neff suffered from advanced Alzheimer's disease, which had tangled the delicate fibers within his brain cells, limiting his speech.

After Neff died on Sept. 11, 2000, a doctor employed by the facility signed his death certificate, citing a "failure to thrive" due to "dementia" as the reason for his demise.

The physician, Anne Whalen, would later testify that she hadn't seen Neff for 13 days before his death. She wasn't at the assisted-living home when he died and never saw his corpse.

Still, it was perfectly legal in Pennsylvania for Whalen to decide how Neff had died and what should be written on the death certificate.

Neff's family arranged for his body to be transported to a funeral home to be prepared for burial. The moment the funeral home's director, Jeffrey Thompson, saw the corpse, he knew something was wrong.

"I'm no CSI expert, but I've been doing this for 25 years, and I've seen a lot of dead people," Thompson recalled. "He was all bruised up and purple, and his ribs were all broken." A bruise stretched from the man's left hip to the middle of his torso.

Thompson contacted the Bucks County Coroner's Office, urging staffers to perform an autopsy. The autopsy showed that some kind of violent impact had snapped five of Neff's ribs. One of the broken bones had pierced his left lung, flooding his chest with blood. The damage was fatal.

If Thompson hadn't spoken up, Neff's injuries probably would never have been detected.

"It could've fallen through the cracks," said Joseph Campbell, the Bucks County coroner.

The autopsy spurred county prosecutors and police to launch an 18-month criminal investigation, which eventually led them to Heidi Tenzer, an employee at the assisted-living facility.

Prosecutors accused Tenzer of stomping on Neff's chest, charging her with third-degree murder, neglect of a care-dependent person and aggravated assault. In 2003, a jury convicted Tenzer of the charges; three of her former colleagues were convicted of related offenses.

Attorney David Zellis prosecuted Tenzer. "Dr. Whalen's testimony was interesting because she didn't know the first thing about" Neff's death, Zellis recalled.

Whalen did not return calls from ProPublica and PBS "Frontline" seeking comment.

Zellis was astounded that a doctor could legally determine how Neff had died without actually seeing his body. "I was stunned," said the attorney, who is now in private practice. "To this day, I find it outrageous."

Ageism and Autopsies

Erroneous death certificates and faulty reporting practices are partially responsible for few senior deaths being investigated. But there's another factor: Many coroners and medical examiners resist looking into these cases.

Of the 1.8 million seniors who died in 2008, post-mortem exams were performed on just 2 percent. The rate is even lower -- less than 1 percent -- for elders who passed away in nursing homes or care facilities.

To a certain extent, the statistics reflect medically reasonable assumptions. The death of a young person is inherently unusual. By the time people reach their 60s, 70s and beyond, aging and disease have caught up to them, and death is more expected.

But Hawes, the Texas A&M professor who studies elder abuse, thinks the numbers also reflect bias. For a 2005 report to the Justice Department, Hawes interviewed 40 coroners and medical examiners about how they handle deaths among the elderly. In anonymous sessions, they voiced deep reluctance to autopsy seniors.

"Many of them made the blanket assumption that when an elderly person dies, it must have been because 'their time had come,'" she said. "But they don't make that assumption about any other part of the population."

In many jurisdictions, coroners and medical examiners are already struggling to autopsy the bodies coming into their morgues. Bringing in more seniors would further stretch their overtaxed resources.

"Coroners will say, 'We don't have enough money to autopsy every old person who dies,'" said Dr. Laura Mosqueda, a professor of geriatrics at the University of California, Irvine, and co-director of the Orange County Elder Abuse Forensic Center. The problem, she said, "is that coroners around the country are using the fact that they can't autopsy all older people who die as an excuse not to autopsy any older person who dies." She trains coroners and their investigators to zero in on signs of abuse and target their efforts strategically.

Some death investigators think concerns about elder abuse and neglect are overblown.

Dr. Jon Thogmartin, the chief medical examiner for Florida's Pasco and Pinellas counties, takes on more than 500 senior deaths per year, ordering full autopsies or checking bodies for external signs of injury. Thogmartin said "95 percent" of the elder abuse allegations he comes across "are completely false," and that many of the claims originate with personal injury attorneys.

But others in the field worry that some coroners and medical examiners may not be distinguishing fatal conditions caused by disease and aging from those caused by abuse and neglect.

When younger people wind up in the morgue, death investigators typically have a clear trail to follow. Was the person shot? Killed in a car crash? Beaten? Did he or she overdose on painkillers?

With seniors, however, they must hunt for more subtle clues. Harruff, the King County, Wash., medical examiner, teaches seminars about finding the forensic signs of elder abuse or neglect.

Some of his colleagues "don't take jurisdiction over neglect cases," Harruff said. "I take the attitude that these are potential homicides."

When Harruff scrutinizes an older person, he checks out the stomach to see if the person had eaten recently. He tests eyeball fluid to see if the person was getting enough to drink. Often, seniors who are neglected or abused are malnourished or dehydrated.

Harruff takes X-rays to search for broken bones, but he also looks for evidence of osteoporosis, which can cause bones to fracture easily without any sort of violence.

Harruff pays close attention to the body's hygiene and cleanliness, and takes note of what the person was wearing. He gets concerned when he finds a senior clad in filthy clothes who hasn't bathed recently.

It's never simple separating the damage done by natural processes from damage done by other people. "In an elderly individual, invariably there's a combination of processes -- if there's neglect, there's usually disease and neglect," he said.

Decubitus ulcers, better known as pressure sores or bed sores, are a possible indication of abuse or neglect. If a person remains in one position for too long, pressure on the skin can cause it to break down. Left untreated, the sores will expand, causing surrounding flesh to die and spreading infection throughout the body.

People with limited mobility are at greater risk of pressure sores. For patients in nursing homes, sores can mean that staffers aren't turning or moving them enough, a serious violation of accepted standards of care. Federal data show that more than 7 percent of long-term nursing-home residents have pressure ulcers.

The wounds can kill, notes Dr. James Lauridson, the retired chief medical examiner for the Alabama Department of Forensic Sciences. "Very often, that is the way these folks die," he said. "It is a preventable mechanism of death that we're missing."

Lauridson, who now performs autopsies for private clients, added, "Occasionally, there are elderly people who are being assaulted. But this issue of pressure ulcers is a far, far bigger issue, and really nationwide."

'I Don't Think We Understood the Level of Poor Care We Would Find'

There is a model for conducting elder death investigations effectively. It has taken root in Arkansas, thanks to the unyielding efforts of a man named Mark Malcolm.

In the late 1990s, while serving as the coroner of Pulaski County, which includes Little Rock and the surrounding area, Malcolm received a string of complaints about seniors dying in nursing homes under suspicious circumstances. He ordered the exhumation of six people, all of whom had supposedly died of natural causes.

The autopsy results were stunning: Four seniors had been killed by suffocation; two had died from medication errors.

Malcolm's experiences prompted him to push for a new state law requiring nursing homes to report all deaths, including those believed to be natural, to the local coroner. The law, enacted in 1999, authorizes coroners to probe all nursing-home deaths, and requires them to alert law enforcement and state regulators if they think maltreatment may have contributed to a death.

In the first four and a half years after the measure's passage, Malcolm reported 86 deaths to other authorities. The number represented a small fraction of the roughly 4,000 nursing-home deaths he and his staff investigated, but it was big enough to suggest there were widespread care problems.

"I don't think we understood the level of poor care that we would find. It came fast, it came furious," recalled Malcolm, who now runs a private disaster management consultancy.

After a death, Malcolm's investigators would visit the nursing home, taking photographs, reviewing medical records and looking for potential signs of poor care such as multiple pressure sores, undocumented injuries or unsanitary conditions.

They found such problems repeatedly at Riley's Oak Hill Manor North in North Little Rock.

Lela Burns remembers watching her mother, Irene Askew, rapidly deteriorate during the four and a half months she spent at Riley's in 2000. Admitted for rehabilitation after hip surgery, Askew soon developed ghastly pressure sores, including one that resulted in the amputation of her lower right leg. Askew died on Nov. 17, 2000. Malcolm ordered an autopsy, which concluded that another massive pressure sore had contributed to her death. The hole was the size of a fist and so deep it exposed bone on her lower back.

"It was a horrible place," said Burns. "You think to yourself, 'How could this happen?' It was just devastating."

The home came to a financial settlement with Askew's family, the terms of which are confidential.

The same year Askew died, another Riley's resident died with five pressure sores so severe they were deemed to be potentially life-threatening. Yet another died with 28 pressure sores. Riley's executives told the Arkansas Democrat-Gazette that they had done everything possible to meet government standards and had an explanation for every complaint. Malcolm's investigations led state regulators to shut down the facility, in part because of the home's failure to prevent and treat pressure sores.

A 2004 review of Malcolm's efforts by the U.S. Government Accountability Office concluded that the "serious, undetected care problems identified by the Pulaski County coroner are likely a national problem not limited to Arkansas."

Malcolm's initiative prompted Medicare inspectors to start citing nursing homes for care-related deaths and to undergo additional elder-abuse training.

Still, nursing homes inspections are not designed to identify problem deaths. The federal government relies on state death-reporting laws and local coroners and medical examiners to root out suspicious cases, said Thomas Hamilton, director of the Survey and Certification Group at the Centers for Medicare & Medicaid Services.

So far, other states have not followed Arkansas' lead. Its law remains the only one of its type in the country, according to experts who track legislation that affects elders.

Another Approach

While Malcolm focused on nursing homes, investigators in some communities are developing new strategies for pinpointing suspicious deaths that occur in private residences.

In 2007, Ingham County, Mich., formed an elder death review team made up of police, prosecutors, adult protective services, the medical examiner, emergency personnel and others to evaluate cases.

Across the country, several counties have created such panels, including King County in Washington, and San Bernardino, San Diego and Los Angeles counties in California. It's an idea borrowed from child-abuse investigators, who have established similar multidisciplinary teams to probe the deaths of young children.

Shortly after Ingham County's team began meeting, Margaret Robinson, 94, died at her home in Lansing, the county's largest city.

Robinson had been living with a man paid $220 a month by the state to care for her.

Since Robinson died at home rather than in a medical facility, a police officer paid a visit to the scene, as is customary in most places. Piles of clutter littered the home, and the place reeked of dog feces and cigarette smoke. Robinson's shriveled body, clad only in a T-shirt and an adult diaper, lay on a bed. The officer would later testify that he didn't spot "any type of foul play," so he called the medical examiner to collect the body.

That's when Connie McQuaid, an investigator with the medical examiner's office, got involved.

Fresh from a training session on how to detect elder abuse, McQuaid spent the night combing through Robinson's medical records.

She spotted "red flags" in the files, she recalled in an interview. Robinson's paid attendant, Ira Gudith, had failed to provide her with medication or diapers. Doctors had noted that Robinson looked "very thin" and emitted a "foul odor." McQuaid said she was bothered by "what appeared to be a lack of concern about her well-being. ... He was not attending to her daily needs."

McQuaid voiced her concerns to supervisors and police detectives. The medical examiner ordered an autopsy.

Forensic pathologist Brian Hunter found that Robinson was emaciated, weighing just 82 pounds, dehydrated and covered with pressure sores festering with staph and E. coli bacteria. Her brain displayed the signs of advanced Alzheimer's disease. These problems contributed to her death.

But the chief cause, Hunter said, "came as a surprise."

Tests of Robinson's blood showed lethal amounts of morphine. No doctor had prescribed it for her, and it seemed impossible that in her bed-ridden state Robinson could have gotten the drug herself.

Criminal charges quickly followed, and in October 2007, Gudith pleaded guilty to second-degree murder. He appealed the conviction and lost.

Gudith's lawyer, Paul Toman, said in an interview that his client had struggled to meet Robinson's mounting needs. "Ira's just a simple fellow," Toman said. "He was in way over his head."

For Ingham County, Gudith's arrest proved the value of its new approach.

"Without the elder death review team, this case would not have gotten the attention of the autopsy team. It would not have gotten the attention of the prosecutor's office," McQuaid said. "This man would have gotten away with murder."

ProPublica's Krista Kjellman Schmidt, Joe Kokenge, Sergio Hernandez and Marshall Allen contributed to this report.

This spring, PBS “Frontline” and ProPublica will explore how flaws in the American system of death investigation have left the elderly vulnerable to neglect, abuse and even murder and how a small cadre of innovators are working to bring such cases to light.