Murder In The Alps Season 2 is yet to be announced by Channel 4

The conclusion of the crime documentary asks why so much attention was focused on prime suspect Zaid Al-Hilli, who was eventually released without charge. Former senior investigating police officer Mark Preston turns the case on its head with a surprising new theory, and other investigators examine whether the killer could still be found, almost a decade after the shootings.

The second episode sees Saad Al-Hilli's brother Zaid arrested on suspicion of conspiracy to murder, and follows leads that take investigators to Switzerland, Iraq and the USA. Detectives hunt for a motorcyclist with a distinctive helmet spotted near the crime scene, the FBI help to uncover a secret marriage, journalists dig into connections with the Iraqi regime, and police find a Swiss bank account containing almost a million euros.

Documentary exploring the 2012 murder of British computer engineer Saad Al-Hilli, his dentist wife Ikbal, and her mother Suhaila in the woods near Lake Annecy, a case that has gone unsolved for 10 years. Caught up in a media whirlwind, Saad's brother Zaid was eventually arrested under suspicion of conspiracy to murder and accused of organising the killings of his brother and family over an inheritance dispute.