Judith Young vanished from her husband's property in Gunningbland, near Parkes, sometime after December 5, 1999. She was 40 years old.

A stream of strange tip-offs, reported sightings and a named "person of interest" have emerged in the quarter-of-a-century since.

This month, NSW Police revealed the case is set to be reviewed.

"Anyone in the community that may have fresh information to assist us in progressing our inquiries is urged to come forward," a spokesperson told the Central Western Daily.

The Orange-raised singer and country music manager - who went under aliases including Judith Henry, Judith Boland and Judy Davis - was reported missing almost two years after she last made contact with family.

In 2009 a handwritten letter was sent to police containing information investigators allege could only be known by someone directly tied to her disappearance.

"What's in the letter - I won't tell you exactly - but [there is] an acknowledgement by the author that they know something," Parkes police crime manager Paul Jones told journalists at the time.

The CWD has spoken to a lead detective from the initial homicide investigation Operation Ullswater. NSW Police declined to give him permission to be interviewed on the record for this story.

An inquest in 2015 turned up multiple leads but delivered an open finding. It identified Judith's husband Phillip Young as a "person of interest".

Several secret affairs allegedly had by Ms Young were uncovered in the process, as were long-term business dealings described as "less than honest, even fraudulent".

In late 1999 or early 2000 - soon after the last confirmed sighting - the missing woman reportedly contacted a close friend, urgently requesting a loan of $680 because "someone was going to kill her".

Her husband has consistently denied any involvement in the disappearance and told police he believes she likely relocated to Queensland.

An extensive search of his property near Parkes in 2008 failed to turn up a body, despite a team of sniffer dogs and more than 50 State Emergency Service (SES) workers. Guns and documents were seized.

"I'm hoping [the inquest] doesn't uncover anything," he allegedly told officers at the time. "The last thing I want to find out is that something happened to her."

In March the CWD left a letter requesting an interview at the Gunningbland home, which is still registered in Mr Young's name. The letter has been collected but no response was provided.

Reports the missing woman was seen alive at the Free Spirit Caravan Park in Darwin in 2010 culminated in a week-long investigation in the Northern Territory. It found the reported sighting was likely unrelated to the case.

NSW Deputy State Coroner magistrate Sharon Freund said the missing woman is dead, but delivered an open finding at the 2015 inquest.

"Ms Young's death is in my view suspicious," magistrate Freund said.

"There remains troubling aspects in relation to the evidence provided to police by Mr Young regarding the disappearance of his wife that does not sit with other evidence heard during the course of this inquest.

"Accordingly, he remains a person of interest."