Police were called to a previous domestic incident two days ago, at the home where a toddler was found murdered.
The body of the boy, who has not yet been formally identified, was found in the early hours of today when officers went to a semi-detached house in Wythenshawe, Manchester.
Officers had responded to a report of domestic disturbance and it has emerged that police went to the address in Beaford Road on Friday after a similar incident.
A 31-year-old man is being questioned on suspicion of murder while police are waiting to speak to a woman who is in a serious condition in hospital.
Both the man and woman had left the property to go to hospital by the time police arrived at the quiet residential area.
Superintendent John-Paul Ruffle, of Greater Manchester Police, said the investigation was at an "early stage" and he could not disclose many details of the case, including the age of the victim - although he described him as a young toddler - and the nature of the injuries.
A post-mortem examination is expected to take place later.
"We have had one previous domestic incident reported on August 25 and that investigation was still ongoing.
"A self-referral will be made to the Independent Police Complaints Commission (IPCC)."
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