The hunt follows information given to police suggesting a death in 2020 at a house on Clarence Road in Handsworth, Birmingham.
A man, 40, and a woman, 41, have been charged with neglect and are on bail after arrests on suspicion of causing or allowing the death of a child.
West Midlands Police said the man had been remanded after appearing in court.
Det Insp Joe Davenport said: "We have acted swiftly on information and our inquiries are ongoing to establish exactly what has happened.
"I understand that this will come as a shock to the local community but I would ask you not to speculate on the circumstances."
Anyone with information is urged to get in touch with police.