According to the National Police Agency (NPA), Japan’s annual total of suicides dipped below 30,000 people for the first time in 15 years in 2012 — to 27,766. While the fall is great news, part of me wonders: Has there really been a drop in suicides or should we look at it as a drop in homicides?

According to the government’s 2012 “White Paper on Suicide,” in 2011 there were 30,651 cases recorded of people taking their own lives. The motives listed were in the following descending order of problems related to health; daily life; family; and work.

But here’s an odd thing: The reasons for the suicide were only determined in 73 percent of cases — in more than 25 percent of cases they were for reasons unknown. Many of those cases perhaps presented no reason because they weren’t suicides at all.

According to the NPA, since 1998 there have been 45 cases of murder initially ruled by police to have been due to natural causes or suicide. Among those, one was a man from Nagano Prefecture whose murder in 1980 was treated as a suicide until the killer confessed in 2000 — after the statute of limitations had passed.

The NPA has admitted that in Japan only 10 percent of suspicious deaths result in an autopsy. However, when a death initially appears to be due to suicide, only 5 percent are autopsied. The lack of a comprehensive use of autopsies was only brought to the public’s attention after several cases of “missed murders” came to light. The 45 known cases may just be “the edge of the graveyard” as some cops have put it.

The most sensational case in this respect is that of Kanae Kijima, who has been convicted of killing three men after swindling them out of their money. She might have been arrested earlier if police had only seen to it that an autopsy was carried out on her first victim, in 2009; he was at first thought to have committed suicide via carbon monoxide poisoning.

Sometimes suicides are only found to be murders after a criminal confesses past crimes, or they come to light after an arrest for different charges. Of the 45 overlooked murders since 1998 the NPA has admitted to, 16 were committed to gain life-insurance money. Although the NPA would not give specific numbers, it said several of those were originally considered to be suicides.

In Japan, suicide pays out — if you wait long enough. That’s because in 2005 most life-insurance companies set the time period for the suicide exemption clause at three years after the taking out of a policy, though some set shorter periods. Hence if you kill yourself past the exemption period, the firm has to pay out.

The Supreme Court of Japan ruled in March 2004: “Even if the reason for suicide was to collect insurance money, if it falls past the exemption period, the company cannot refuse to pay.”

In a bizarre case in 2009, the Sendai Lower Court ordered a ¥50 million payout for an attempted suicide where the insured died from injuries sustained during the act. The result is an incentive for people to kill themselves — and also an incentive to kill people and stage it as a suicide.

In August 2000, a member of the Ground Self-Defense Force was strangled to death and the case was treated as suicide by hanging, based on the false testimony of his wife and the failure of the Miyagi Police to distinguish between the marks of hanging versus strangulation. The life-insurance payout was more than $1 million.

A 52-year-old office worker killed in 2009 in the city of Matsudo, Chiba Prefecture, was made to write his own “suicide note” before being hanged. When police arrived at the scene, they found the note, which explained that the deceased was “upset about his debts.” The case was treated as a suicide and the beneficiary of his life-insurance policy later collected a ¥20 million payout.

Why didn’t these cases arouse suspicion?

A homicide detective noted to this writer that until recently life-insurance companies have not been at all enthusiastic about cooperating with murder investigations. “If you put in a request for information about the deceased, it took them days or weeks to respond. By the time you find out something irregular about the insurance, often the body has been cremated — evidence gone. Highly likely there was no autopsy. We don’t have the staff or budget to do more.”

According to the Sankei Shinbun newspaper, it was only in June 2012 that The Life Insurance Association of Japan finally agreed to fully cooperate with police requests for information on the insurance status of the deceased in cases of suspicious deaths. It is a step forward in preventing insurance-driven murders.

As a result, police checks are expected to quadruple to nearly 27,000 a year. However, the new measures won’t be implemented until April this year at the earliest, when a unified data system goes online.

In a recent conversation, an employee of a major life-insurance company explained — in blunt terms — why the sector hadn’t been giving full cooperation to the police before: “Suicide and natural death are cheap, murder is expensive.

“If it’s ruled a suicide, we may be able to avoid paying at all. Plus, in many cases, the insured may have a large-sum accidental-death benefit. Guess what? Being killed counts as accidental death.”

The insurance man said even if the new system takes off, it may not detect all the murders disguised as suicides. “We’ve agreed to cooperate fully with the police. However, it’s pretty much, ‘If you ask, we’ll tell.’ If the police don’t ask, that’s it.

“It makes good business sense, but morally it’s pretty awful. Yet what do you expect from a business that bets on life and death.”

Another man in the business of life and death, a medical examiner with a police department in the Kanto region, has his own pet theory about the apparent decline in suicides. “People who want to leave the life insurance for their family are better at killing themselves and making it look natural. You can buy a manual or go online and learn how. They know if their deaths are labeled suicide their families get nothing.”

He says that families often ask police not to report a death as a suicide, and the police tend to comply. “Here’s the reality of the situation, if it looks like a natural death — that’s how it gets treated. If it superficially looks like a suicide, you take a lot of flack if you suggest it’s something else. Even if we do an autopsy, unless there’s some glaring irregularity, we sign it out as ‘heart failure.’ In our business, that means ‘we don’t know the cause of death.’

“And then we’re on to the next body.”

Jake Adelstein is an investigative journalist and author of the bestselling “Tokyo Vice.” He contributes to The Atlantic Wire and the Japan Subculture Research Center, and is a Polaris Project Japan board member. He can be contacted at jakeadelstein@me.com.