Leng was last seen catching the train home to the southwest Sydney suburb of Campsie, where she lived with her 48-year-old auntie and the accused since arriving in Australia five years ago.
Leng kept in contact with friends until late that Thursday night, before her phone and social media accounts fell silent. Three days later, a tourist discovered her lifeless body in water more than 100km away.
It's understood the accused and Leng's auntie first reported her missing on the Monday, a day after her body was discovered.
Police will allege Barrett murdered the young woman at Campsie while his wife was away for the weekend, some time between 4.45pm local time on April 21, and 10.30am on April 24.
It's understood Barrett is originally from the Central Coast town of Gwandalan, which is about 9km from the dangerous blowhole, popular among tourists and fishermen.
His next court date has been set down for Burwood Local Court on Wednesday where he's expected to appear via video link.
Leng's mother flew into Sydney on Saturday as the university student's family and friends mourn her violent death.
The student was known as Michelle in Australia and was an economics student at the University of Technology Sydney.
Strike Force detectives released CCTV video of Leng shopping at Pitt Street in Sydney at about 3pm on April 21.
Less than an hour later she is seen catching a train from St James Railway Station, arriving at Campsie Railway Station about 4.30pm.
Police believe she never made it to the Campsie home.
Chatter on social media sites this week suggested Leng had plans to meet up with somebody she had met online.
The last Instagram picture she took is of children enjoying a man blowing giant bubbles in front of St Mary's Cathedral in Hyde Park.
Friends and family have left dozens of messages next to the photograph, which is time stamped "1 week ago" and was likely taken on April 21.
The scene is not far from St James Station.
Since the tragic news of her death, friends have paid tribute to Leng on Chinese social networking site Weibo.
"Michelle and I were classmates for four years, I still can't believe this, I still can't accept that it's true! I hope that the police will quickly solve this case and give us the facts. Rest in heaven, and be reborn in paradise, RIP," one wrote.
Another hoped this tragedy would be a lesson to other Chinese students studying abroad.
"Learn to take care of yourself in dangerous situations! Be careful! Be careful! And I'll say it again - be careful! I hope that this kind of thing won't happen again and also hope that the deceased can now rest in peace. RIP."
Another person who posted to Weibo hoped it wasn't a deliberate murder directed at Chinese people.
Leng's heartbroken parents have told Chinese media of police descending on their daughter's home.
"(They) took away her toothbrush, collected hair and other personal items to do DNA comparison, today the police took away Michelle's computer to find more effective clues," they said.
- news.com.au, AAP
