Six women have been arrested on suspicion of manslaughter after a one-year-old boy died at a nursery.
The tot was being cared for at Fairytales Day Nursery in Dudley, West Mids., when he collapsed at 3.20pm on December 9.
Ambulance crews scrambled to the nursery in Bourne Street after receiving reports he had gone into cardiac arrest.
Despite attempts to resuscitate the boy, he died at the scene.
A post mortem has taken place but further tests will be conducted to establish the exact cause of death.
West Midlands Police say they are treating the death as "suspicious" and have arrested six women.
Three women – aged 20, 23 and 50 – were arrested on December 16 on suspicion of gross negligence manslaughter.
They were subsequently released on bail with strict conditions while enquiries continue.
A further three women – aged 51, 53 and 37 - were arrested on Wednesday (4/1).
Two were arrested on suspicion of corporate manslaughter and one on suspicion of gross negligence manslaughter.
Police launched a criminal investigation following an Ofsted inspection after the boy’s death.
In the Ofsted report, concerns were raised about the “safeguarding and welfare requirements” at the nursery.
Inspectors temporarily closed the nursery and made nine recommendations which included better training for staff.
They also raised concerns that they were not informed of a change of manager at the nursery.
Staff were told to check sleeping babies more frequently, putting babies down to sleep in a safe way.
Inspectors said staff should have “appropriate qualifications, training skills and knowledge” with regards to sleeping children.
In a worrying observation, the report said staff should “take all reasonable steps to ensure children in your care are not exposed to risks, paying particular attention to risks in the baby room.”
The nursery opened in 2003 and cared for children from as young as three-months. It received a ‘Good’ Ofsted report last February.