This series takes an in-depth look at some of the world's most prolific serial killers and interviews those who were closest to them before learning about their secret, dark lives. Attempting to uncover the psychology of each killer – from Jeffrey Dahmer to the DC Sniper – "TWISTED" tries to get an understanding of what drove these serial killers down the path of murder. Was it nature or nurture? Through first-hand accounts and testimonies of the people who knew them best, this series provides fascinating insight into the characters of some of the most infamous icons of evil. (Source: Investigation Discovery)