In the fourth episode, Rinder examines the murder of Cassandra Valentin by her fiancé Marvin Williams. Williams and Valentin had begun dating in 2004 but their relationship quickly became violent, and Valentin filed a number of domestic violence injunctions against Williams over the years.In 2013, he was sentenced to four years in prison but was released again in 2016 and the pair resumed their relationship. On 21st January 2018, Valentin was found in her home having been stabbed multiple times in her neck and stomach. Emergency services found her lying on the floor in the hallway, with a broken piece of the knife blade still in her neck.On the day after the murder, Williams left a voicemail for his sister that indicated he had killed his girlfriend, and he immediately became the prime suspect.