National Missing Persons Week to highlight long-term missing Australians

He went missing after visiting a family member's home - vanishing without a trace.

The disappearance was heart-breaking. The pair, who were both adopted and only 15 months apart in age, were inseparable as children.

"We were really close, really close," Ms Sushames said.

David's disappearance is described by police as out of character, with foul play suspected.

It's a theory Ms Sushames agrees with - while she was not in regular contact with her brother, this was unlike what he would do.

"He had a block of land at Sheffield (on Tasmania's north west coast), he was going to build a house up there," she said.

"I'd nearly bet my last cent that he's come to foul play, because it wasn't like him to just disappear. He'd keep in contact every now and again and he had two kids.

"He wouldn't have just left. There were no Centrelink transactions, no bank transactions - just nothing."

Not knowing what happened to her brother Ms Sushames said was challenging, and something that impacted her to this day.

Ms Sushames said theories and rumours about David's disappearance had floated around over the years, and that her and her mother, who is now 91 years old, just wanted answers about what happened - no matter how painful they were.

"It's hard, it's really really hard," she said.

"It niggles me all the time. I don't know, and I'll never know.

"I just want some answers ... I don't want to know really what happened to him, but on the other hand I do want to know for closure."

The pain of losing David had eased throughout the years, with dates and anniversaries slowly hurting less as time passed on, but something the family said will never truly go away.

Ms Sushames said she believed there were people out there that knew something about her brother's disappearance, and that there were people that could contribute to the investigation of his case.

"It's always in the back of your mind, what's happened to him," she said.

"Someone out there knows something."

David is one of 168 long-term missing people in the state, dating back to the 1950s, and is one of seven being highlighted by Tasmania Police during National Missing Persons Week.

Sergeant John Delpero, from the Tasmania Police Missing Persons Unit, said the week of action was aimed at profiling long-term missing persons, and raising awareness of the issue.

"While a number of missing persons will be highlighted this week, it is important that we remember all our missing persons and the pain felt by their families and loved ones," he said.

Also highlighted are Craig Taylor, reported missing from Coningham at age nine in 1993; Michael Lenssen, age 48, who was last seen at a Launceston CBD business on 30 March 2020; Nancy Grunwaldt, who was reported missing from North-East Tasmania in 1993 at age 26; Robert Mansell, age 42, reported missing from Flinders Island since 2015; Gilbert Midson, last seen in Hobart in 1964 at age 23; and Zedric Woolley, missing from Huonville since 2012 at age 81.

"As police officers, our aim is to locate missing persons and bring answers," Sergeant Delpero said.

"A missing person case is never closed until the person is located.

"Even in instances where the disappearance of a person is reported to the Coroner, the case remains open.

"This week I urge anyone with information about any missing person to please come forward and help us provide some kind of closure to the families and loved ones of the victims."

Ms Sushames urged anybody who thought they may have any information about a missing person to come forward.

"It doesn't matter how small it is, or how insignificant they think it is, they could be the answer," she said.

"Hopefully this report sparks someone's memory, and we can get some answers for these people and their families too."

Information relating to a missing person can be provided to Tasmania Police directly on 131 444, or anonymously to Crime Stoppers on 1800 333 000 or online at crimestopperstas.com.au.