A couple have been arrested on suspicion of murdering a one-year-old boy they were set to adopt.
Police said a 37-year-old woman and 34-year-old man, from Barrow-in-Furness, Cumbria are also accused of causing or allowing the death of a child and two counts of assault.
Cumbria social services said the baby was under its care but was living with the couple before the adoption.
The pair are suspected of ill treatment, neglect, or abandoning a child or young person to cause unnecessary injury.
They were released on bail while detectives investigate the circumstances.
Detective Chief Superintendent Dean Holden, head of crime and safeguarding at Cumbria Constabulary, said: “Two people have been arrested as part of an ongoing investigation into the tragic death of a one-year-old boy in Barrow.
“On January 6, police received a report from North West Ambulance Service regarding an incident at a property in Barrow.
“The child was transferred to Alder Hey Children’s Hospital from Furness General Hospital for specialist medical care due to his critical condition.
“Sadly, the young boy passed away on the afternoon of January 7.
“An investigation is under way by a dedicated team of detectives and other specialists in order to establish the full circumstances of the death in full consultation with the coroner.”
John Readman, executive director of people at Cumbria County Council, said: “This is a deeply distressing case and our thoughts are with the little boy’s family.
“We can confirm that he was looked after by the local authority and at the time of his death was placed with adoptive parents.
“The county council, as part of the Cumbria Safeguarding Children Partnership, has recommended that a full independent safeguarding review is carried out.
“A police investigation is also ongoing, and so we are unable to make any further comment at this stage.”
The Adoption and Children Act 2002 says a child must live with adoptive parents for a period before an application for an adoption order can be made.
When a child is placed with adopters, they assume legal parental responsibility but the child remains “looked after” by the local authority until an order is granted.