A baby who died after being rushed to hospital from a house in Liverpool died of serious head injuries.
Police were called by paramedics to a house in the Speke area of the city on Friday.
The child was taken to hospital, but sadly later died.
A 23-year-old man from Winsford, Cheshire, has been arrested on suspicion of murder, reports the Liverpool Echo.
He remains in custody for questioning today, Merseyside Police confirmed.
Teddy bears and other tributes had been left outside the house on Belsford Way, where the baby lived, this morning.
Detective Inspector Sabi Kaur said: "I would like to pass on our sincere condolences to the boy's family following this tragic incident.
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"The family are being supported by specialist detectives at what is obviously an incredibly difficult time for everyone concerned. Our thoughts are with all of those affected, and we will continue to investigate the circumstances."
Anyone with information is asked to contact Merseyside Police on 101, quoting reference 19100375517 or Crimestoppers, anonymously, on 0800 555 111.
