No arrests have been made or charges laid in relation to the missing boy.
Detectives said they no longer expect to find Gus alive when they revealed bombshell details of their ongoing investigation.
Detective Superintendent Darren Fielke said there had been “discrepancies” and “inconsistencies” in the information provided by some of Gus’ family members.
“As a result of these inconsistencies, and investigations into them, a person who resides at Oak Park Station has withdrawn their support for the police and is no longer co-operating with us,” he said.
Fielke said the suspect was not one of Gus’ parents.
“The person who has withdrawn their co-operation is now considered a suspect in the disappearance of Gus,” he said.
“I do want to stress, however, that Gus’ parents are not suspects in his disappearance.
“I can’t give you any more information about the suspect or where the suspect is and why that person is a suspect.
“When we have a suspect in an investigation, it can … have its own challenges, so we’re working through those.”
The little boy’s grandparents hired separate lawyers after the new details were revealed.
Gus’ grandparent Josie Murray has hired criminal lawyer Andrew Ey, and his grandmother Shannon Murray is being represented by defence lawyer Casey Isaacs.
The legal team confirmed on February 6 they were representing Gus’ grandparents.
“Andrew Ey and Casey Isaacs can confirm that we act for Josie Murray and Shannon Murray respectively,” the lawyers said.
On behalf of the boy’s grandparents they said: “We are absolutely devastated by the media release of SAPOL Major Crime.
“The family has co-operated fully with the investigation and want nothing more than to find Gus and reunite him with his mum and dad.”
It is not unusual for potential witnesses to seek legal advice.
There is no suggestion that Josie or Shannon Murray were involved in Gus’ disappearance.
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