What Do Bodies Tell Us? Forensic Pathologist Hirotaro Iwase on Postmortem Changes, Overlooked Causes of Death, and the Limits of Japan's Death Investigation System

Medically, death is declared when three conditions are met: dilated pupils, cardiac arrest, and respiratory arrest. According to Iwase, however, it is actually difficult to determine precisely "at what moment" a person died. Even when the heart stops, it doesn't stop all at once; it can keep twitching, almost convulsively, for some time.

After death, the body undergoes changes that correspond to the passage of time. As Iwase explains, livor mortis begins to appear after about an hour. Gravity pulls the blood downward, so if the body is lying face up, the back takes on a reddish tinge. Body temperature also drops by roughly 0.5 to 1 degree Celsius per hour. After about 12 hours, most postmortem changes are well established. Rigor mortis, in which the body stiffens and can no longer move, sets in, and the corneas become clouded, with the dark part of the eye turning whitish.

After about a day, rigor extends throughout the entire body. Iwase describes the stiffness this way: if you rested the head on one chair and the feet on another, the body would not bend but would stay perfectly straight, supported between them.

Alongside rigor, decomposition begins immediately after death. In the case of "land bodies" — those found not in water or in soil but, for example, inside a home — the smell of decomposition is quite intense; Iwase likens it to a powerful blue cheese. Putrefactive gases build up throughout the body, and when they accumulate in the abdomen, it swells up tight. Urine is forced out of the bladder, gas collects in the blood vessels as well, and fluids seep outward and disperse. As a result, it is normal for decomposed bodies to have no blood or urine left. In summer, some bodies have lost their blood and urine within about a day, but in autumn, Iwase says, blood often remains for two to three days.

Regarding bodies of people who died in water, Iwase explains that most initially sink because they take in water and lose the air in their lungs, and then often float to the surface later once decomposition causes gas to build up. It isn't unheard of for a body to float from the start. Because water enters the airway through the throat, triggering a choking reflex as the person loses consciousness, Iwase believes drowning is likely a very painful way to die. On the other hand, death by fire is also a terrible way to die — every one of them is a terrible way to die, Iwase says.

Iwase has also seen, from a distance, the body of a person who died from radiation. In the 1999 JCO criticality accident at a uranium processing facility in Tokai, Ibaraki Prefecture, three workers were exposed to massive doses of radiation, and two of them died. Since the case occurred in Ibaraki Prefecture, the autopsy should normally have been performed at the University of Tsukuba, but for some reason it was carried out in the pathology autopsy room at the University of Tokyo, jointly by a University of Tsukuba professor and a University of Tokyo pathologist — a highly unusual arrangement. Iwase, who was then in the University of Tokyo's Department of Legal Medicine, watched from a distance. The skin appeared badly sloughed and raw. With a burn, the damage is present from the beginning, but with radiation injury, there are no visible changes at first, and then damage spreads here and there. In that sense, Iwase said, it is eerie.

Over more than 30 years in forensic medicine, Iwase has personally performed autopsies on probably around 3,000 bodies, and around 9,000 when including those handled in a supervisory role guiding colleagues. Iwase is accustomed to bodies on the autopsy table, in the sense of being able to stay calmer than someone who has never seen one.

That familiarity, however, is limited to the autopsy table. When a body is on the table, Iwase can switch into work mode, but when encountering a body anywhere else — someone lying on the ground after jumping to their death, or hanging in a toilet stall — Iwase says they become a layperson again and feel a strong sense of dread.

Sometimes a body reveals how the person lived. A simple example is tattoos. Some people have full-color tattoos completed to the end, but many have pieces that were never colored in. Seeing the latter, Iwase sometimes imagines that the person ran out of money partway through, or did something that got them kicked out of their gang.

A person's lifestyle also shows in their organs. If the blood vessels are smooth and the kidneys on the large side, Iwase wonders whether the person was a heavy drinker. If the lungs are clean, Iwase thinks the person may have lived in the countryside. The lungs of smokers and of people who lived in cities like Tokyo are usually black. Iwase began practicing forensic medicine in Tokyo before moving to Chiba, and recalls feeling at the time that the lungs of people in Chiba Prefecture were cleaner than those in Tokyo. Iwase added, however, that it's hard to say nowadays, since cars have become cleaner. Cirrhosis of the liver is clearly recognizable by its bumpy surface, and alcohol-related cirrhosis has a slightly yellowish tinge.

As for methamphetamine, Iwase has the impression that for some reason it has long been used steadily in Japan. Characteristic signs include a very high body temperature at the time of examination, injuries all over the body from thrashing in a delirious state, and, often, a thin build.

Compared with the past, Iwase feels that more young people are dying of overdoses. Iwase says cases in which two or three people who met online and agreed to "die together" are found dead in the same room from overdoses or carbon monoxide poisoning are also a very contemporary way of dying. Iwase performs many autopsies on suicides, and each time wonders whether something could have been done.

Iwase points out that many deaths also cause harm to others. When hydrogen sulfide suicide became a trend, many people followed the manual and posted "Danger" signs at the bathroom entrance. But hydrogen sulfide is heavier than air and flows downward, Iwase asks — so what about the residents on the floor below? Iwase said they always wish young people would stop taking their own lives.

The traces on a body can also reveal the truth behind a crime. Iwase once performed an autopsy on the body of a woman found on the banks of the Edogawa River, burned black, with her head sawn off at the neck. It was obvious she had been burned to destroy evidence. The autopsy found no soot in the trachea, which showed that she had been burned after death rather than alive. And because the cut surface was not charred, it could be determined that the head had been removed after the burning.

The police began treating it as a murder and initially suspected that she had been strangled. Iwase was asked again and again, "Wasn't it strangulation?" and found it very stressful. Eventually, one to two months later, the head was found, and the skull was fractured. The perpetrator was arrested, and it turned out that the woman had been killed by being struck on the head with something like a bat.

According to Iwase, when there are no fatal external injuries such as stab wounds, the police tend to want to call it strangulation, because strangling is the quickest way to kill without leaving marks. When the cause of death cannot be determined, investigative convenience and forensic judgment sometimes don't line up. Iwase warns that acting on preconceptions can lead to irreversible consequences later.

In an autopsy, the external findings on the body are recorded first. In addition to height, weight, and nutritional state, livor mortis, rigor mortis, and rectal temperature are recorded, and every injury and bruise on the body is checked one by one. Then the head, chest, and abdomen are opened, the organs are removed and weighed, and they are examined for disease and injury.

According to Iwase, even a body that hasn't decomposed takes at least two hours. The more injuries there are, the longer it takes: a traffic accident can take five hours, and a victim of a frenzied stabbing can take 12. That's because each stab wound must be measured and photographed, and investigators must trace the direction in which each wound was inflicted and which organs it damaged.

As an example of a careful autopsy overturning the initial assessment at the scene, Iwase cited a body found in the mountains of Chiba Prefecture. The case fell under the jurisdiction of the police station farthest from Chiba University. Iwase explains that it is said internationally that the farther a place is from where autopsies are performed, the lower the autopsy rate, noting that the difficulty of transporting bodies lies behind this.

When a family member failed to come home, a search of the forest turned up the body of an elderly woman. Her arm had a hole that looked as if it had been gnawed by a wild boar, and the local station reported to headquarters that she had died after being bitten by a boar. But a coroner from headquarters, unable to understand how a boar could kill a person, went to the scene; the cause of death couldn't be determined, so an autopsy was ordered. Buckshot was found in her head. The investigation revealed that a hunter who had come to cull wild boars had reacted to a noise, spun around, fired, and shot the woman. Realizing he had hit a person, the hunter had fled the scene.

Conversely, a crime can sometimes be hidden in a death thought to be from natural causes. Paramedics were called to a person who had collapsed on a sidewalk, and the person went into cardiopulmonary arrest during transport. A CT scan at the hospital revealed a subarachnoid hemorrhage, and the doctor concluded it was a death from illness. In this case, however, someone had witnessed everything and told the paramedics, "This person was punched in the face and has been lying here ever since." Because the paramedics notified the police, the case wasn't missed.

Iwase says that this is something hospitals should notice, but when a hospital finds a subarachnoid hemorrhage, it tends to classify the death as natural. For that reason, Iwase suspects that quite a few murders are being missed through hospital diagnoses. Hospitals also cannot tell when someone has been drugged. Unless the system shifts toward police ordering autopsies for deaths of unknown cause, crimes can go undetected. To make that happen, Iwase argued, the government needs to create an environment in which forensic pathologists can perform autopsies.

At the time of the Tokyo subway sarin attack on March 20, 1995, Iwase was 28 and had been a forensic pathologist in the University of Tokyo's Department of Legal Medicine for a few years. The attack happened during or just before Iwase's commute, and on arriving at work, Iwase found department members gathered around the television in an uproar. Early reports described it as something like a bombing, but soon reports emerged that sarin had been detected, and the next day bodies were brought in for autopsy. Iwase didn't even know the nerve gas called sarin existed and had to start by looking it up.

The autopsy room was filled with police officers, and staff from the National Research Institute of Police Science — apparently there to detect sarin in the organs — as well as prosecutors from the Tokyo District Public Prosecutors Office were waiting. There had already been reports that a police officer who approached a body at the scene had blacked out and collapsed. Although the bodies' clothing had been removed, the autopsy proceeded with the worry that it might be dangerous if a large amount of sarin remained in the lungs. Iwase's mentor at the time, Professor Takatori, performed the dissection, with Iwase assisting. Iwase recalls being extremely tense when the professor opened the area around the trachea leading to the lungs, wondering what would happen if something came out.

Autopsy findings alone, however, could not establish sarin poisoning. The police wanted it declared a death by sarin. Amid this, word got around that a professor at another university was apparently saying, "I could diagnose sarin." The method involved examining nerves under a microscope, but according to Iwase, such a diagnosis is absolutely impossible for an acute death from sarin. Iwase surmises that Professor Takatori probably felt the need to prove a point by some other method. The professor began by developing a way to actually detect sarin as a substance, along with its metabolites. Later, sarin metabolites were detected in the victims' tissue, providing scientific evidence linking sarin to the cause of death.

At the time, however, the only drug-testing equipment at the University of Tokyo was a gas chromatograph for alcohol testing, and it could not detect any other drugs. Iwase says that while they were amazed by Professor Takatori's dedication, it was around this time that they began to feel, very strongly, toward the government: "What is this place?" Looking back now, Iwase believes that a great many drug-related deaths must have been missed in the past.

A few weeks before the Great East Japan Earthquake in 2011, Iwase had been exchanging emails about the identification of Japanese victims in New Zealand with a doctor who was then a professor in the Department of Legal Medicine at Iwate Medical University. A newspaper had run an article to the effect that New Zealand's backward procedures were delaying the return of bodies to the families in Japan.

According to Iwase, careful identification is only natural. Other countries require a match on at least one of three things: fingerprints, DNA, or teeth. In Japan, by contrast, if a family member looks at the face and says, "This is them," the body is handed over. But faces alone can lead to mistakes, and if a mistake is made, the shock later is even greater. In the exchange, the Iwate Medical University professor wrote, "Sooner or later, something like another Sanriku earthquake will happen, and when it does, we'll need to do proper identification. I'd really like the people at Chiba University to help too." The earthquake struck shortly afterward.

Because the death toll was so high, the Japanese Society of Legal Medicine and the National Police Agency coordinated to dispatch forensic pathologists to perform postmortem examinations alongside police inquests. Chiba had also been hit by the disaster, but as a university relatively close to Tohoku and with enough personnel, it sent Iwase to Iwate first. The team of ten — three physicians, three dentists, and four police officers — left on the night of the day after the earthquake. The Tohoku Expressway was badly damaged, and they repeatedly drove at highway speed, braked hard, and crept over the uneven sections. The service areas were almost deserted, with only fire and police vehicles parked there. They bought rice balls amid shelves still stocked with unsold goods and arrived on site the next morning.

Bodies had already been laid out in a gymnasium. On one side of a row of ping-pong tables, the bodies were examined; on the other side, family members had come to search for their loved ones. Working amid the sound of crying was extremely painful, Iwase says. Among the dead were babies and high school boys and girls, and the psychological stress was immense.

What Iwase kept thinking about while working was whether it was really right to call them all drownings. Even if they were drownings, weren't there some that could have been prevented? Many people died in their cars, with no injuries on their bodies, as the cars filled with water. Some might have survived by breaking the window glass and getting out — though some might also have been crushed by debris after getting out. Even so, Iwase wondered whether some measures could be devised to save lives. If deaths were caused by hypothermia, the countermeasures would be very different.

In fact, it seems that some of the dead had died of hypothermia. A later newspaper article reported that some people had died overnight at the civic hall in Rikuzentakata. Iwase and the team must have examined those bodies too, but because they had all been recorded as drownings, there was no way to tell which ones they were. "I have nothing but regret," Iwase says. But individual regret doesn't solve the problem. Even if not every body can be autopsied in a disaster, examining a sample would reveal what proportion of deaths were due to hypothermia. Had that been known, countermeasures could have been put in place, and if deaths were drownings inside cars, other measures might have saved lives, Iwase believes.

Iwase had sensed the system's shortcomings from the moment of starting in forensic medicine. Iwase came to forensic medicine after nearly a year of training in internal medicine. In internal medicine, blood tests and CT scans are routine, so why couldn't they be done in this field? From their earliest days as a newcomer, Iwase thought that someday it would have to become standard to diagnose bodies by CT before autopsy. But there was no money, and a CT scanner was out of reach. In the case of the headless burned body mentioned earlier, the head was later scanned using a hospital's borrowed MRI, but that was an exception; CT and MRI scans were not done routinely.

When Iwase took up a professorship at Chiba University in their tenth year in forensic medicine, the facilities were far worse than at the University of Tokyo. The university received no autopsy funding at all; every autopsy was done for zero yen. On top of that, the incorporation of national universities was coming the following year. Once incorporated, there would be even less money — but Iwase also thought it might be possible to bill the police, and submitted a request asking that costs be paid after incorporation. The precedent-bound bureaucracy, however, ignored it, treating it as: you've done it for free all along, so why bring this up now? At that point, one official said, "The public isn't interested in death investigation, so there's no way the Ministry of Finance will fund it."

So Iwase used the entire 2.5 million yen research budget that had been allocated to each department before incorporation to rent a mobile CT vehicle for five days at a cost of 2.5 million yen. The idea was that by accompanying police on their inquests, they could find cerebral hemorrhages among cases diagnosed as heart failure and show that the recorded causes of death for Japan's "suspicious deaths" and "unnatural deaths" were completely different from reality. At the time, Iwase questioned being in a position where they had to teach students how interesting forensic medicine was without being able to run any tests, and was losing sight of the point of continuing. Iwase says the resolve was to strike one last blow before quitting — and if that didn't work, to really quit.

As a result, in two weeks, four or five cases were found to have a different cause of death. This led the media to recognize the problem and contributed to subsequent improvements. Then came the Tokitsukaze stable case, in which a crime at a sumo stable had initially been missed; because it was a scandal in sumo, the national sport, the death investigation system came to be debated in the Diet as well. Costs began to be paid, and some improvements followed, Iwase says. Drug testing is now possible too. DNA testing, however, was taken away midway because the National Police Agency didn't want to pay for it, Iwase says, adding that they carry on while dealing with that kind of stress.

Through these developments, postmortem CT spread into death investigation practice. According to Iwase, however, CT yields a diagnosis in only 20 to 30 percent of cases, and in the end an autopsy is still necessary.

Moreover, forensic medicine thinks about cause of death differently from other doctors. There is the immediate cause of death and the underlying cause of death. For example, even if a person ultimately died of a cerebral hemorrhage, if that was caused by methamphetamine intoxication, the underlying cause is methamphetamine intoxication — making it a poisoning death, and in some cases a murder by methamphetamine. Finding a cerebral hemorrhage on CT is not the end of the story. For that reason, Iwase explains, the idea of simply using CT for screening is difficult to realize from a forensic standpoint.

According to the program's narration, roughly one in eight people who die in Japan becomes the subject of a police investigation into the cause of death or possible foul play. Asked whether people die easily, Iwase answered that they have seen many people killed in disputes, and that accidents are common too. Some people drown in water just tens of centimeters deep, and others die of a broken neck with barely a scratch on them, which sometimes makes Iwase wonder how someone with so few injuries could have died. On the other hand, some people survive being hit by a car. Even so, Iwase says, you can probably reduce your risk of dying quite a bit by avoiding dangerous places and staying out of fights.

To the final question — what is death? — Iwase answered that there is no doubt everyone will die. But unless it's suicide, hardly anyone can predict when, where, or how they will die. That is exactly why, Iwase said, it's probably best to spend our time while we're alive enjoying ourselves and getting along with everyone.