Police have released CCTV footage in the hope of finding out what happened in the hours before the death of a toddler in North Queensland.
The two-year-old was brought to Mackay Base Hospital about 8pm on December 29.
Detective Acting Inspector Chris Eaton said the girl was declared dead later that evening.
He said police believed the child was unwell in the hours leading up to her death.
A crime scene was declared at the toddler's home in North Mackay for several days.
"Part of our investigation centres around those days leading up to the child's death, and in particular the care that was provided to the child in those days," Acting Inspector Eaton said.
Police released CCTV footage on Friday showing the toddler being carried in a harness on a woman's back through Andergrove Coles and United Chemist on December 29.
Shoppers are seen walking past the group, and it these people police are urging to come forward.
"We believe that they may have seen something in relation to the deceased child, or may have had conversations or interactions with the persons who are depicted," Acting Inspector Eaton said.
The footage shows about five individuals near the group, including a man in high-vis work gear and a woman carrying a black backpack with a man at the chemist.
The footage from the freezer section in Coles shows a woman with a black T-shirt and leggings and a teenaged boy.
Acting Inspector Eaton said even if someone was not in the footage but was at the chemist between 3.50pm and 4pm or Coles between 4pm and 5.30pm, they were encouraged to contact police.
He said the investigation was a "major police investigation", with detectives from the Mackay Child Protection and Investigation Unit (CPIU) being assisted by the Child Trauma Unit, Crime and Intelligence Command.
Police can be contacted via Policelink on 131 444.
