THE body of 21-month-old toddler Mason Jet Lee was covered "from head to toe" in injuries.
The boy's body was found at a Caboolture South home on June 11, about 12.30am, but police said it's believed he may have died hours earlier.
Speaking at Police Headquarters in Brisbane, Detective Acting Inspector Ben Fadin said Mason death was "tragic" and "horrific".
"And it's something we are determined to resolve," he said.
Officers from the Homicide Investigation Unit (HIU) and Child Trauma Task Force have joined the Moreton District Child Protection Investigation Unit in investigating the boy's death.
Police have spoken with 40 people as part of the investigation.
Det Act Insp Fadin said post mortem results indicated Mason's death was unlikely to have been a result of an accident.
"As such we are continuing to treat it as suspicious," he said.
"Mason suffered severe injuries and may have been sick for a number of days or even weeks prior to his death."
Det Act Insp Fadin said Mason suffered injuries that would have been visible to anyone who saw him prior to the day he died.
"He suffered extensive injuries, they were horrific, and they were visible from head to toe," he said.
"We can say Mason may have been sick or injured for up to a week before he died."
Symptoms he might have suffered included being lethargic, vomiting, not eating his food and generally being unwell.
Police are trying to piece together what happened on the night of Mason's death, and in the months leading up to it.
They are urging anyone who may have seen Mason or his carers, or had any contact with them from January 1 to June 11, to speak to police.
"We know Mason was part of a big family in the Caboolture area and known to many people," Det Act Insp Fadin said.
"We are urging anyone who had interactions with Mason at any time this year or has any information about his death to contact investigators directly or call to Crime Stoppers on 1800 333 000," he said.
Det Act Insp Fadin said no matter how small or insignificant an interaction might have seemed it could be important.
"It may be that small piece of information that we need to progress our investigation," he said.
In investigation centre has been set up at Burpengary Police Station.
Anyone with information that could help police with the investigation should phone Crime Stoppers on 1800 333 000.
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