A man has been charged with the murder of a nine-year-old girl after a child's body was found stuffed in a barrel and dumped in a river near where the schoolgirl went missing last week.
The girl, who can no longer be named due to a charge being laid, had been holidaying with family at Wildenstein Private Gardens in Mount Wilson, near the Blue Mountains.
More than 100 police and emergency personnel - including dog units, homicide detectives, rescue choppers and volunteers from the SES and Rural Fire Service - scoured the surrounding area for five days.
On Tuesday, police divers found the body of a child in a barrel while searching a stretch of the Colo River.
A crime scene has been established and is being examined by specialist forensic officers, who are working to formally identify the child.
Police arrested the 32-year-old man at a Surry Hills unit on Tuesday night.
Justin Laurens Stein faced court on Wednesday morning, where his lawyer detailed a long history of mental health problems.
At a press conference on Wednesday, police said Stein became the focus of their investigation after "inconsistencies" in his story appeared.
"Special behaviour" also caught police's attention.
"Those movements included on Thursday afternoon - after a number of telephone conversations with a girl's mother - to purchase a number of 20kg sandbags from a hardware store, to fuel a boat, and then try and float that boat... at one of the docks in inner Sydney," Deputy Commissioner David Hudson said.
When that was unsuccessful, police tracked the man back to the area the girl's body was eventually found.
Police hope to speak with the girl's mother - who is receiving health care - but say there isn't any evidence to suggest Stein had an accomplice.
Investigations are ongoing, with police yet to determine how the girl died and any motive for her murder.
Dep Com David Hudson said the case is as awful as it gets.
"We start off these searches with a lot of hope but, unfortunately, we always have in the back of our minds the worst," he said.
"It's been a very difficult search for those involved."
Deputy Premier and Police Minister Paul Toole called the case "horrible", "horrific" and "shocking", while Prime Minister Scott Morrison sent his prayers to the girl's family.
"I can't imagine what the parents and their community have been going through," he told reporters.
"You hope for the best, you pray for it, but it doesn't always occur, (and) my thoughts and prayers frankly are with the family today."
NSW law prevents the public identification of children who are victims of crime.
Last seen on Thursday, police weren't alerted to the girl's disappearance until Friday when a family member enquired about her whereabouts.
Detectives from local police and the homicide squad had also spent extensive time at the property interviewing the family.
A neighbouring resident told AAP his wife had been reading early on Friday morning when she heard a car heading up the road without headlights.
"She went to the window and got out of bed and saw through the trees the shadow (of the vehicle)," the neighbour said.
"People go out at night and usually have headlights."
Interstate relatives of the girl had called for information to assist the missing persons case.
Earlier in the search police had expressed some hope that recent rain meant there would be puddles of water in the bush that could sustain the girl until she could be found.
But as investigations turned towards human intervention, police limited their public appeals, holding their last press conference over the weekend.
The Wildenstein Private Gardens sit at the end of a road in the small village of Mount Wilson, which is home to about 100 people and a host of hospitality areas.
