In the US, Rebecca Fenton murdered her husband and staged a break-in. Her calm, image-obsessed behaviour masked a chilling psychology. She was sentenced to life in 2015.

In the US, Ali Abulaban, a former airman, abused Ana Abulaban, then killed her and her friend after she left him. He was convicted of two counts of first-degree murder.

US model Kelsey Turner's 'Sugar Daddy' scheme turns deadly when she and boyfriend, Jon, murder Dr Burchard after financial betrayal and false accusations.

In the US, Brian Cohee Jr. murdered a local man, hid body parts, and later confessed. Obsessed with violence, he was sentenced to life in prison.

In the US, Dr Milner's obsession led to the stalking of Tanya and Kenny. After court orders failed, he murdered Kenny and was sentenced to life in prison.

Bryan Whitelock killed a friend and his brother, later murdered his neighbour Wendy Buckney, and was sentenced to life with no parole.

Lori Isenberg poisoned her husband but told authorities he had drowned, to cover up her fraud. She was eventually caught and pleaded guilty to second degree murder.

In East Sussex, UK, Lewis Ashdown murdered YouTuber Marc Williams after pressuring him to drink excessively. He filmed the entire attack and was and sentenced to life in prison.