The "good old nail method" when you wanted to commit the perfect murder.
Apparently, the "nail method" used to be quite popular when you wanted to get rid of someone discreetly.
Before there were X-rays, it was hard to tell that someone had a nail in their head.
The victim's hair hid the tiny marks covering the wound, and so people who saw no obvious signs of injury often assumed it was a natural death.
The nail method is so ancient that it is already mentioned in the Bible, Book of Judges 4:21:
Then Jael, Heber's wife, took a nail from the tent and a hammer in her hand and went quietly to him and drove the nail into his temple and deep into it, for he was fast asleep and tired. That is how he died.
The nail method is also mentioned in very old Chinese literature.
The picture above is an X-ray from 1973.
A man had driven an awl into his wife's head with a hammer, explaining that he was doing this to "exorcise the evil soul that had settled in her head.