Christopher Dean Watkins has been missing for nearly eight years.

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While his body has never been found, police believe the 28-year-old was killed after disappearing from a unit in Box Street at Mayfield on August 7, 2013.

Police now know Mr Watkins made a panicked phone call to a family member the night he disappeared, telling them two men he had history with had arrived at the unit where he had been staying with friends.

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That was the last time anyone heard from him.

When the investigation was launched, at least six men provided statements to police. But some of those statements were lies. Four men later faced charges of conspiracy, and perverting the course of justice.

A woman was eventually convicted of failing to report Mr Watkins' killing, and making a false police report, and a second person was charged with failing to report a killing. But, to date, nobody has been charged with his murder.

On Monday, Northern detectives were expected to share an update on the case, and it was understood they would ramp up their investigation into the unsolved mystery.

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When the woman convicted of failing to report Mr Watkins' killing appeared in the Launceston Supreme Court in 2016, details of her interviews with police were revealed.

Initially, she lied to police telling them her brother, and two other men had been at her home the night of Mr Watkins disappearance.

The woman referred to the two men only by nicknames.

But she later admitted only her brother had turned up, shaking and upset.

Her brother told her he and Mr Watkins had been taken from his house, hog tied and put into the boot of a car before being driven to bushland, ripped from the car, forced to drop to their knees and interrogated, and threatened by the two men, she revealed.

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That was when, according to the woman's brother, Mr Watkins "would not cooperate", and he was "roughed up and shot and told to run".

In a sentencing report by Justice Shan Tennent, it was also revealed the woman told police her brother was forced to watch and then help bury Mr Watkins.

"[They] came to your home and wanted to know if your brother had spoken to you," Justice Tennent wrote.

"Over following days those men drove past your house several times and were pretending to fire a gun.

"Despite being told by your brother that he had witnessed the killing of Watkins you did not make any report to police. You only told the story when interviewed by police in August 2015."

The woman was sentenced to nine months in prison, wholly suspended. But the two men she spoke of have not yet been charged.

Police had been confident several people were involved in the suspected murder.

Mr Watkins remained listed as a missing person, with a $50,000 reward for information relating to his disappearance still on offer.

Anyone with information should contact Crime Stoppers anonymously on 1800 333 000.

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