Missing boy, 4, feared dead in Australia after police identify suspect at family home

Gus Lamont was last seen playing outside his family home on a sheep farm near Yunta in South Australia on September 27.

Officers looking into his disappearance say the person they are now looking to speak to lives on the remote property, but added it is not one of his parents.

Read more: Cyber security student, 20, stabbed to death at De Montfort University

Read more: Captain of tanker jailed for six years over fatal North Sea crash

Gus vanished after his grandmother left him alone for half an hour at the Oak Park Station property, before raising the alarm when she returned to find he had gone.

His disappearance triggered one of the largest land and air searches ever launched in the state, with officers and volunteers trawling over an area roughly twice the size of Edinburgh (470 square kilometres).

After finding no trace of the boy, police scaled back their search operation in October and streamlined their investigation into a 12-member taskforce.

Detectives has since reviewed statements given by Gus's family members, leading police to "identify a number of inconsistencies and discrepancies" in the timeline surrounding his disappearance.

This has led the force to identify a suspect at Oak Park Station, Detective Superintendent Darren Fielke said.

"As a result of these inconsistencies, and investigations into them, a person who resides at Oak Park station has withdrawn their support for the police and is no longer cooperating with us," he said.

"The person who has withdrawn their cooperation is now considered a suspect in the disappearance of Gus."

At the time of his disappearance, Gus' grandmother, grandparent, mother and younger brother were known to be on the property.

"I do want to stress, however, that Gus's parents are not suspects in his disappearance," Mr Fielke said.

"You appreciate at this time I cannot make any further comment about the suspect, given that this is now a criminal investigation and a declared major crime.

"What I can say, however, is that we'll continue to thoroughly and meticulously investigate the disappearance of Gus until we get an outcome."

Police seized a number of items, including a vehicle, motorcycle and some electronic devices, during a search of the property in January.

Investigators said they had initially considered three possible scenarios - the boy walked off, he was abducted, or someone known to Gus was involved in his disappearance and suspected death.

Police were quick to rule out abduction given the remote location of the property and said there was no evidence to suggest Gus had "merely wandered off".