These days, the spooky skeletons you sometimes see in doctors’ offices are generally made of plastic. But that wasn’t always the case, and if the medical textbooks you read are old enough, you can still find explanations of how to make your own – starting with the ominous instruction to “acquire a corpse.”

Maybe that was what Shoichi Murai, a 68-year-old Tokyo resident recently arrested after throwing his dead brother's skeleton in the trash, had in mind when he presented his defense: he thought it was a fake.

According to VICE World News, Murai claims that he had not seen his younger brother since 2017 – despite the siblings living in the same house. With a view to selling, he says he was cleaning the house when he went into his brother’s room and saw what he assumed was a model of a skeleton lying on the bed. He threw out the skull and jawbone but left the rest of the bones on the bed.

Sounds suspicious? You might be surprised: “I have heard of many people who have said that they thought a skull was fake when it was real,” Diane France, a forensic anthropologist and director of the Human Identification Laboratory of Colorado who is not involved with the case, told IFLScience. 

“Some of those people aren’t being truthful, of course, but I think some people who just don’t see many bones in nature might think that some real bones were actually fake,” she said.

Garbage collectors spotted the defleshed head, plus one of the brother’s credit cards which had also been tossed, and notified the police. Murai was arrested Friday on charges of abandoning a corpse – a charge which Japanese police sometimes invoke while they investigate whether murder should be added as well.

While investigators have not announced any information on what the cause of death may have been, an autopsy revealed no significant external injuries to the body, VICE reports. “If there were unnatural marks on the […] skeleton, then depending upon those marks, it might be an indication of foul play, animal predation, etc,” explained France.

One piece of information that has been released is a limit on the time of death: the brother had been dead at least a few months by the time his body was found. Amazingly, even that relatively short timeframe may be long enough for a body to decompose: “The factors that determine how long it would take for a body to become skeletonized include temperature, humidity, solar radiation (which probably isn’t an issue here), wind (ditto), insect activity (possible), etc., so it isn’t a precise timeline,” France explained – but studies have shown that bodies left inside can decay and skeletonize very quickly under the right conditions.

Although the story may seem farfetched, it wouldn’t be the first time something like this has happened. “I have heard stories about someone living in the same house (or even in the same bed!) with a corpse and didn’t report it,” France told IFLScience. 

“For example, an elderly couple near Denver had oxygen delivered periodically for the husband.  When the oxygen supply arrived on schedule, the delivery people couldn’t even enter the house because of the smell of decomposition,” she said. “They called law enforcement and the coroner, and they discovered that the woman’s husband had died some time previously […] he was significantly decomposed with flies and maggots.”

That would be bad enough to live with, but the story gets even more gruesome: “the wife, who had dementia, continued to sleep with her husband,” France told IFLScience. “[She] reported to law enforcement that she just thought he had become a deep sleeper!”

“It is difficult to believe that someone with a normal mental capacity would ignore the telltale signs of a decomposing brother a floor above in a home, though,” France concluded. “I would be curious to know that tidbit.”