WATCH: Police investigate children's deaths in Morayfield
POLICE are investigating the alleged murder of two children and alleged attempted murder of two other children in the one Morayfield family.
Between July 2013 and September 2014, a three-year-old was reported dead to police, two children were believed to be impeded from escaping a deliberately lit fire, and a seven-month-old child was also found dead.
Police regard the children's grandmother - who they said was present at all incidents - as a person of interest, but no charges have been laid.
Detective Acting Superintendent Damien Hansen said although police had not initially believed the three-year-old's death to be suspicious, they were now investigating it as murder.
Det Acting Supt Hansen said a reconstruction of the fire by police and firefighters found it had been lit on purpose and the children's bedroom door had been deliberately kept shut.
"Forensically we're able to say the fire was deliberately lit and that the children's access or escape from that room was deliberately impeded. We are treating that as an attempted murder and arson investigation," he said.
He said the alleged murders were among the most horrible he had encountered.
"I'd regard murder as one of the most serious offences, if not the most serious offence that can occur. To have it happen to defenceless children is just mind-boggling," he said.
Det Acting Supt Hansen would not be drawn on the causes of death, but confirmed the children were members of the same family.
The alleged murder of the three-year-old child occurred on July 27, 2013, the alleged murder of the seven-month-old child on September 27, 2014, and the alleged attempted murder of the other two children, aged nine and 11, overnight on February 27, 2014.
Det Acting Supt Hansen said police were investigating the significance of the 27th day of each month, but did not believe there were any religious or cult links. He called for anyone with information to come forward.
- APN NEWSDESK