The Leader can reveal detectives have upped the ante in the historical missing person investigation which is now a murder probe, and are investigating leads in the Tasmania and South Australian areas as they try and find out what happened in 1993.

New England Detective Inspector Roger Best said the drug supply information had become the lead line of investigation for officers.

"Of course when there's drugs involved there is money involved; when there is money involved, there's motive," Detective Best told the Leader.

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The specialist team of police - code-named Strike Force Annan - have already been to the two locations, but believe there is key information missing about what happened to Bill in 1993.

"Police firmly believe he had become involved in drugs," Detective Best said.

"We believe he may have got out of his depth and may have found himself in a situation that he couldn't manage."

The new developments come three weeks on from an emotional appeal by his sister to find him, and the announcement of a $1 million reward for clues.

The strike force is remaining tight-lipped on much of the detail of the probe, only to confirm they do have persons of interest.

"We have information that showed he was involved in drug supply to a level that would have put him in danger," Detective Best said.

"And that is why we firmly believe he met with foul play."

William 'Bill' Roach was just 25 years old when he was seen walking along a street in Armidale on New Year's Eve, 1993, looking casual in a red flannelette shirt and blue jeans.

Then, he vanished without a trace.

Last month, the Leader revealed more than 100 people had been spoken to as part of several new leads.

For the past seven months, detectives from Armidale have travelled to Hobart, Brisbane, Adelaide, Kangaroo Island, Melbourne, Sydney, Griffith, and the NSW North and South Coasts to interview a list of people who could hold crucial clues.

"There's been numerous contacts made since the appeal with various lines of inquiry," Detective Best said.

"There is still people who have information out there concerning what happened and we need to speak to them.

"Our priority is finding him and what happened."

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The mysterious disappearance of Bill in 1993 has been the focus of Strike Force Annan since it was first launched in 2004. The historical missing persons case was re-opened when new information was handed to police then.

Detectives then had a small breakthrough in 2010, and again in 2016, but the mystery has never been solved.

In February, Bill's sister Kim Roach told media that their mother Yvonne had passed without ever knowing what happened.

"My brother Bill, missing for 27 years, missed for 27 years, still loved immensely," she said.

"The loss, the unanswered questions, the not knowing, the no closure.

"We still live with the hope someone will come forward with information - big or small. We live with the hope for closure, the hope to be able to grieve and to lay my brother Bill to rest, please."

Australian Community Media has exclusively interviewed Mr Roach's late mother and one of the original men questioned over the murder mystery. In 2016, the strike force dug up a property on the outskirts of Armidale, as part of one lead which went dead.

A podcast exploring the Bill's disappearance has been created, called William Allan Roach, and police said it "turns up new evidence that takes the case in a fresh direction after three decades". They're hoping someone out there might know more.

Episodes are on Listnr https://bit.ly/37ABLSI.

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