Yang Xinhai was a Chinese serial killer who confessed to committing 67 murders and 23 rapes between 1999 and 2003.

He was sentenced to death and executed.

He was dubbed the "Monster Killer" by the media. He was the most prolific known serial killer in China since the establishment of the People's Republic of China in 1949.

In this week's episode, we dive deep into the crimes this disgusting man committed. Additionally, we will discuss the re-eduction camps in China as the perpetrator was sent there several times before committing the murders and rapes. Also touching on other infamous serial killers habits and what it means to be a serial killer.

In the second part of the season 4 finale, we dig deep into the investigation of Lucie's disappearance.

A grueling 7 month search took place before Lucie's body was eventually found under a bathtub inside a seaside cave.

The shocking discovery came when a man named Joji Obara was reported by several other hostesses who came forward and complained of waking up feeling sore and drugged. After police arrested him, they found hundreds of video tapes of him assaulting women, and the discovery of a woman named Carita Ridgeway who died at the hands of Obara.

It was a mission to find this man guilty of kidnapping and murdering Lucie Blackman.

It should have been a dream trip, two 21-year-old friends from the UK moved over to Tokyo for a gap year to work and live in one of the most exciting cities in the world. Less than 2 months later, one of the women, Lucie Blackman, went missing after going on a dohan (a paid date in Japan) with a man who approached her whilst she was working as a hostess in a club in Roppongi.

With mass media attention, and a 7 month search, this became one of the biggest cases in missing persons history in 2000. Tragically, Lucie's dismembered body was found underneath a bathtub hidden in a seaside cave on a beach outside of Tokyo.