Some of history's most infamous killers were calm, collected, and fully aware of their dastardly deeds. Others were deeply troubled and unaware of, or incapable of controlling, their actions. For a long time, the law saw no importance in the psychological condition of the perpetrators of crimes, until the mid-19th century. Since then, pleas of insanity have been used in some of the most famous criminal cases in collective memory. Sometimes they were genuine, other times they were used by killers looking for an easy way out, but they were always fascinating.
Read on to learn more about some of the most notable uses of the insanity plea.