Sinister source of the Salem Witch trials is revealed on the eve of Halloween

Theories about what sparked the Salem Witch Trials include everything from a hallucinogenic fungus to psychological disorders and economic conditions. 

But now, scientists may have settled the debate by identifying the sinister source of Massachusetts' 'witch craze' that saw more than 200 people tried and 19 executed by hanging 300 years ago. 

A new study discovered that the invention of the printing press in the 15th century - which drastically increased the spread of information - led to the proliferation of a book that contained a detailed explanation of 'demonology.'

The widely-printed book, Malleus Maleficarum - which translates to the Hammer of Evil-Doers - depicted witchcraft as a 'conspiratorial activity against godly society' rather than benign 'mischief by village sorceresses, pagans, or ignorant peasants.'

This book also served as the first printed guide printed guide for witch-hunters. 

Approximately 36 editions were printed  between 1486 and 1669 in Germany, sparking an outbreak of witch hunts across Europe.

While the book never came to the US, its teachings traveled with colonists who settled in Massachusetts. 

The researchers believe that Malleus Maleficarum's message spread rapidly through 'ideational diffusion,' or 'the adoption of new ideas, which lead social actors to reinterpret the world and thus to change their behavior.'

This was made possible by the German inventor Johannes Gutenberg, who created the printing press in 1440.

This momentous invention quickened the spread of knowledge, discoveries and literacy across the world, ushering in a new intellectual era.

Malleus Maleficarum, written by the Dominican friar Heinrich Kramer, was first printed in 1486 and quickly became one of the most well-read books about witches and an early form of mass media.

Its message spread first through literate members of European society, then to the illiterate through conversation. 

Eventually, the teachings of Malleus Maleficarum made it all the way to the US, ushering in a new perception of witchcraft and mobilizing a wave of persecution unlike anything seen before. 

Witches were present in folklore long before the Malleus Maleficarum was printed, dating all the way back to the ancient Romans. But this book stoked a new level of fear that ultimately lead to tens of thousands of deaths around the world. 

'The book's great innovation was to combine an elaborate theological explanation of witchcraft with practical guidance on the methods of investigating, interrogating, and convicting witches,' according to the study, which was published in the journal Theory and Society.

The researchers mapped the dates and locations of various witch hunts that took place throughout Central Europe from 1400 to 1679, and compared them to where Malleus Maleficarum had been printed and distributed. 

They found that 'Cities closer in time and space to the publication of the Malleus were more likely to commence witch trials.'

The study suggested that the printing press played a key role in the spread of this new perception of witchcraft, and therefore indirectly fueled the 'witch craze' that led to witch hunts across the world, including the Salem Witch Trials.

These infamous trials began when a group of young girls in Salem Village, Massachusetts, claimed to be possessed by the devil and accused several local women of witchcraft.

This incited a wave of hysteria that swept across colonial Massachusetts, and a special court convened in Salem to hold the first trial in 1692. 

The first convicted witch, Bridget Bishop, was executed by hanging that June. 

In the months following her death, more than 200 people were accused of witchcraft and 19 were executed. 

Years later, several of the accusers - most of whom were teenaged girls - admitted that they were lying about the charges. In 1702, the General Court of Massachusetts declared the trials unlawful, and in 1711 annulled the convictions of 22 trial victims.

Today, the Salem Witch Trials are seen as one of colonial America's most notorious cases of mass hysteria.