Julian Ingram, 37, was accused of killing his pregnant former partner Sophie Quinn, her aunt Nerida Quinn and a third person in the western NSW town of Lake Cargelligo on January 22.
There had been no positive sightings of Ingram since he was seen driving out of the town in a white getaway ute on the day of the alleged shootings.
But on Monday, NSW Police revealed they had found the body of a 37-year-old next to a white Ford Ranger, alongside a firearm, at Roundhill Nature Reserve, about 100km northeast of Lake Cargelligo.
While he is yet to be formally identified, the vehicle's registration number matched the ute used on the day of the murders.
Police found the council worker's licence inside the car and the clothing on the body has led officers to believe it is Ingram.
"It's a relief for those involved in the investigation, and probably a bigger relief for the people of Lake Cargelligo and the Quinn family," Western Region Commander Andrew Holland told reporters.
"It brings closure to this investigation, it brings closure to the people of Lake Cargelligo and gives some solace to the town, so they can relax."
Ingram was believed to have committed the murders just hours after reporting for bail at a local police station.
Ms Quinn, 25, and her friend John Harris, 32, were killed when bullets were fired into a dark hatchback on Lake Cargelligo's Bokhara St about 4.20pm.
Soon after, her 50-year-old aunt was shot dead at a home on Walker St, a two-minute drive away.
Kaleb Macqueen, 19, was also shot at the home but survived with serious injuries.
The shootings shocked the region, with locals urged to exercise extreme caution as police launched their manhunt.
For weeks, officers scoured the nearby bushland looking for signs of Ingram, eventually expanding their search to the remote outpost of Mount Hope, a former mining town about 90km northwest of Lake Cargelligo.
As leads dried up, police offered a $250,000 award in March for information that could lead to his capture.
Investigators believed Ingram was alive for at least a week after his disappearance.
But by the time he was found on Monday, it seemed he had died long ago.
"Police have ... located a male body in a very decomposed state," Assistant Commissioner Holland said.
"The body appears to have been there for some time."
Officers will continue investigations into how the death occurred and the state of decomposition will be determined by a coroner.
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