At around 07:30 BST on 24 May 2019, police officers were called to a residential property on Gregg House Road in Shiregreen, a northern suburb of Sheffield, South Yorkshire, following reports concerning the welfare of children.

[3] Two people, Brandon Machin, a 38- or 39-year-old man[i] and Sarah Barrass, the 34-year-old mother of the children, were arrested at the property on suspicion of murder.

The police had received reports of concerns for the safety of a number of children inside the property from neighbours, and initiated a large scale response to the incident.

[1] The area surrounding Gregg House Road was placed under lockdown, including Hartley Brook Primary Academy, whose playground was used for the landing of the Yorkshire Air Ambulance at the scene after the police raid.

[3] Police later narrowed down the cordon to the affected street and confirmed they were not looking for other suspects in connection with the "isolated" incident, with no wider risk to the community.

[3] A press release by South Yorkshire Police later ruled out a shooting, confirming that no shots had been fired and there had not been an incident at the school.

[1] A murder investigation was launched shortly after the initial police raid concluded, with forensic examination of the property and surrounding areas.

[8] In November 2018, an allegation of sexual assault towards another child had been made about Blake, the 14 year old victim, and social services became involved.

Social services were unaware of the children's father and made inquiries into this, and performed the usual screening for any possibility of sexual abuse within the home.

[6] The final trigger may have been a phone call to Barrass on the evening of 23 May, when an unnamed local individual complained of a further sexual assault by Tristan against a child, and that they would be reporting the matter to social services.

The proposals gained the support of the surviving members of the Barrass family as well as the wider local community in Shiregreen.