The Mad Gasser of Mattoon was a mysterious figure who haunted Mattoon, Ill., in the summer of 1944.

Typically, homeowners would report awakening to a sweet odor, then feeling nausea, dizziness, headaches, breathing difficulty, or a feeling of paralysis. Some saw a tall figure dressed in black fleeing their property after the attack.

Police and citizens patrolled the streets, and the newspapers printed several sensational accounts, but the police never found a suspect. The attacks stopped after Sept. 13, as mysteriously as they had begun.

In 1963, Peter Reyn-Bardt killed his wife and buried her in a peat bog in Cheshire County, England. Twenty years later, when a body was discovered, he assumed he’d been caught and turned himself in.

He should have waited. An investigation showed that the body was not his wife’s, but that of an Iron Age man who had died two thousand years earlier and been eerily preserved in the cold acid bog.

They convicted Reyn-Bardt anyway.

Former Argentine president Juan Perón is buried in Buenos Aires. In 1987, someone broke into his tomb and stole his hands.

No one knows why.

On New Year’s Day, 1963, two bodies were found in a lovers’ lane in Sydney, Australia. They belonged to Gilbert Bogle, a top research physicist, and his mistress. Both were partially undressed and covered with clothes and cardboard. Police could find no trace of poison; their hearts had simply stopped beating.

To this day, no one has determined whether they were murdered, and if so, how or why. It is a perfect mystery.

In 1955, the merchant vessel Joyita disappeared en route from Samoa to the Tokelau Islands, about 270 miles away.

A search and rescue mission found nothing, but five weeks later she was sighted more than 600 miles from her scheduled route. The ship was partially submerged and there was no trace of her 16 crewmembers or 9 passengers, including two children.

An inquiry found that the disappearance of the passengers and crew was “inexplicable on the evidence submitted.” But the Fiji Times and Herald quoted an “impeccable source” saying that the Joyita had passed through a fleet of Japanese fishing boats and “had observed something the Japanese did not want them to see.”

What was it? No one knows.