The family of a young Melbourne woman who has been missing in Las Vegas for four months says local authorities have plagued the "lacklustre" investigation into her disappearance with miscommunication and false leads.
Sally Contarino, 26, has not been seen or heard from since June 20, the day she was supposed to fly home to Melbourne from her solo holiday in the popular tourist destination.
Ms Contarino's elder sister Amy lashed the Las Vegas Metropolitan Police Department (LVMPD) for scaling back efforts to locate her sister.
"We're really disappointed in how essentially they're not looking for her anymore," Amy told the ABC.
"I don't think it's good enough.
"There's an online forum of people that are following Sally's case who I believe are doing a heck of a lot more than the detectives are."
An Instagram user captured a video of Sally Contarino in Las Vegas prior to her disappearance. (Instagram)
In the days after she went missing, a large-scale police search was launched that included sniffer dogs and drones, but that has since been wound back as leads on her location dried up.
Ms Contarino, who has functional neurological disorder (FND) — a condition that changes the way the brain receives and sends information to the rest of the body — has been missing for 120 days, making her a "long-term" missing person in the US.
Las Vegas police released CCTV images of Sally Contarino in an appeal for public assistance. (X: Las Vegas Metropolitan Police Department)
Investigators have so far been unable to rule any possible outcomes out of the investigation, including foul play.
Investigators unable to access phone data, family says
Amy still messages her sister, hoping it generates signals police could use to narrow down her location after probes into apps on her phone ran cold.
"I message her every day, even to today, just hoping that it will change from 'sent' to 'delivered' and that I'll hear from her again," Amy said through tears.
"It changes from just how much we love her and just reminding her that we're looking for her every day and just that we're not giving up."
Las Vegas police now believe Ms Contarino was last seen just after 1pm on June 20 in the area of West Skye Canyon Drive, on the north-western edge of the city.
A shopping strip mall is located at the address, and borders the US Route 95 highway leading north-west out of Las Vegas and towards nearby desert.
Amy said police in Las Vegas had so far been unable to access data from Ms Contarino's phone because while she was using an e-SIM to travel, they did not have permission to obtain her Australian phone records.
She said investigators seemed reluctant to fight those administrative obstacles.
"We're not willing to accept that they're unable to ping her phone. I feel like it could answer a lot of questions so for us that's the main thing we want answered at this stage," she said.
Amy claimed slow communication from Las Vegas police had misled her family about her last known location for weeks.
She said investigators told the family they believed her last known location was near Fletcher's Canyon in Mt Charleston after sniffer dogs tracked her scent there during an initial major search. But it has since been revealed that was not the case.
"To find out that she essentially was never there was really disheartening because it kind of opened back up a world of other possibilities."
Ms Contarino's family are raising money to return to the US to continue searching for her themselves.
Amy said her sister, who had travelled to Las Vegas in the past, loved its warm, open surroundings because they eased her FND symptoms despite being alone in a more unfamiliar location.
She said Ms Contarino loved spending time outdoors and with her family, and they had planned to catch up with her when she returned home.
"I would always say to her: 'If I didn't have you, I'd really struggle' because she truly makes me laugh more than anybody. She was … she's just the best person to be around so we really, really want to bring her home," Amy said.
"She's also the funniest person that I know."
Sally Contarino's family say she had travelled to Las Vegas alone before. (X: Las Vegas Metropolitan Police Department)
Amy said her message to the LVMPD was simple: "Please look for my sister and don't give up."
When contacted by the ABC, the LVMPD would not provide an update on the investigation into Ms Contarino's disappearance.
Back in Australia, a Department of Foreign Affairs and Trade spokesman said they were offering Ms Contarino's family ongoing support.