The South Korean police on Tuesday found the car of the three-person family who mysteriously went missing almost a month ago on a remote island.

Ten-year-old Cho Yu-na and her parents, both in their 30s, went missing on the southwestern island of Wando County, South Jeolla Province, on May 31 after they entered the island in a silver-colored Audi sedan on May 23.

An Audi sedan with a matching license plate was discovered off the coast of Sinji Myeon in the region at 05:12 p.m., according to the Gwangju Metropolitan Police Agency and Wando Regional Coast Guard.

The car was overturned with the trunk open when it was found. But the coast guard could not confirm whether Cho‘s family was in the car.

The police plan to pull the submerged car from the sea Wednesday to prevent the loss of belongings and secure evidence that could help the case.

The family of three went missing after Cho’s parents on May 17 reported to her daughter‘s school that Cho would be on a field trip to Jeju Island between May 19 and June 15, the school told the police.

But on the same day, Cho’s parents made a reservation for accommodation at a guesthouse, oddly not in Jeju Island but Wando County. Cho also did not attend school because she was reportedly sick on that day.

Cho failed to report to school after the announced travel period, which prompted school officials to visit her home in Gwangju. Officials filed reports to law enforcement upon seeing her home mailbox full of unopened mail.

The car was found six days later, after a large-scale police search started on June 22. But the police have not yet found conclusive evidence to solve the case.

The family was staying at the guesthouse on May 24 and was last seen leaving the place at around 11 p.m. on May 30 from surveillance camera footage. But the vehicle never left the island, according to the footage obtained by investigators.

Cho and her mother’s last detected cell phone signals placed them at the guesthouse at 00:40 and 1:09 a.m. on May 31, and the signal for Cho’s father was gone at 04:16 a.m. near the Songgok Port on the island.

Meanwhile, South Korean media outlets reported that Cho’s family suffered from financial troubles. Cho’s parents were unemployed after closing their business last year.