Police searching for missing four-year-old Gus Lamont have charged his 75-year-old grandparent Josie Murray with firearms offences but have maintained the charges are not linked to the toddler’s disappearance.

Officers announced the charge this afternoon as they finished searching for the day in a renewed operation at Gus’ family’s Oak Park Station homestead, about 43 kilometres south of Yunta in South Australia.

Gus was last seen playing on a mound of dirt about 5pm on September 27.

SA Police has released the first picture of missing 4-year-old boy Gus Lamont.Gus, four, was reported as last seen playing on a mound of dirt about 5pm on September 27. (South Australia Police)

Police will continue to search for evidence and said they would remain in the area tomorrow.

“An update on the search activities will be provided as they progress,” SA Police said in a statement.

As a result of a previous search at Oak Park Station, police arrested Josie Murray, who was bailed to appear in the Peterborough Magistrates Court on May 6.

Detective Inspector Andrew Macrae said the firearms charges were not related to the disappearance of Gus or a previous incident at Oak Park Station in October involving media attending the property.

Gus Lamont’s grandparent Josie Murray. (Nine)

Police earlier this month confirmed a person with close ties to the household, who is not one of Gus’ parents, had been speaking with detectives but then allegedly “withdrew cooperation” and has since been identified as a suspect.

Gus’ disappearance is now being considered a major crime.

Josie Murray and Gus’ other grandparent Shannon Murray released a statement through their lawyers, saying they were “absolutely devastated” by SA Police’s statement on February 6.

“We are absolutely devastated by the media release of SAPOL Major Crime. The family has cooperated fully with the investigation and want nothing more than to find Gus and reunite him with his mum and dad,” the statement read.

The lawyers also indicated they will not be making any further comments.

There is no suggestion Josie or Shannon Murray are involved in the disappearance of Gus and it is not unusual for anyone linked to an investigation to seek out legal advice.

Oak Park Station missing boy Gus LamontSA Police have returned to the family’s property, known as Oak Park Station. (9News)
Missing four-year-old Gus Lamont in SAThe search for Gus has been the largest missing person search ever undertaken by SA Police. (9News)

The search for Gus

No evidence of Gus has been uncovered despite extensive searches of the property, which Detective Superintendent Darren Fielke said has been the “largest and most intensive” missing person search ever undertaken by SA Police.

A full-scale ground and air search of the property and the surrounding area was launched after Gus went missing.

The search area has totalled 706 square kilometres, with the assistance of 80 Australian Defence Force soldiers, drones, mounted officers and aircraft.

About 163 SA Police officers have been deployed for the search.

A three-day search of six mine shafts near Oak Park Station also failed to uncover any evidence.

Police received more than 150 Crime Stoppers tips about the missing boy.

Officers returned to the area surrounding Oak Park Station to search for Gus’ remains on February 2, but uncovered no evidence.
FULL VIDEO AND SOURCE: https://www.9news.com.au/national/gus-lamont-update-police-return-to-oak-park-station-in-search-for-missing-boy/7d48bf8c-b1ca-4050-ab06-1cf99fc3abd1