With families and friends left searching for clues to the whereabouts of loved ones, Queensland's Missing Persons Unit – a team of nine police investigators – has one of the best recovery rates in the country, at 99.5 per cent.

The unit's Detective Senior Sergeant Damien Powell said every case was taken "seriously" and should be reported to police as soon as there were concerns for one's safety.

"There is no time limit when a person can be reported missing. There is a misconception in the public that they have to wait 24 hours, that's not the case at all, the person can be gone 20 minutes and reported as missing," he said. "Quite often people including the elderly are reported within 20 minutes, a very short time frame.

"What we don't encourage is people being reported missing because people have simply lost contact with them . . . they must have concern for their safety in order for a person to be reported a missing person."

More than 200 long-term missing persons remain on Queensland files and 1600 persons nationally, alongside a constant flow of new cases each week.

National Missing Persons Week, which begins this weekend, will focus on older people with dementia or memory loss who go missing.

Australian Federal Police Missing Persons spokeswoman Leonie Jacques said Australians should be aware of elderly people with medical problems, including dementia, who have a higher risk of going missing.

"Much to the surprise of the general public, out of 35,000 people who are reported missing to police each year, a high percentage are older people with dementia," she said.

"The more common symptoms of dementia are memory loss and wandering which can lead to someone becoming a missing person."

Sen-Sgt Powell said that despite Queensland having no outstanding long-term cases of missing persons aged 66 and over, it was important society remained aware of this high-risk group.

"Retirement villages, families looking after the elderly and identifying people who have tendencies to wander should be aware," he said.

"Concerns can also be raised because of mental health. A person could be suicidal, there could be issues of depression, self harm, or simply because of their age they could be a missing person."

While some missing people chose to simply "stay underneath the radar", Sen-Sgt Powell said this could make it difficult for police to track down a missing person. "Australia is a very big country and the geography is against us in a lot of matters," he said.

"We have had a number of missing persons who have been on a hunting trip in the Outback and have never been seen again.

"All our fishermen who go missing overboard are listed as missing persons and the file does go to the coroner but they remain on our books as missing persons."

So far this year there have been nine marine incidents from as far north as Thursday Island and south to Bundaberg in which people remain missing.

The Missing Persons' Week campaign will include a series of television, print, radio and internet announcements and will run until next Saturday.

Source: news.com.au