It's a story of love and loss, of war and a horrific crime.

Almost 50 years after Lucille Butterworth was abducted and murdered in Tasmania, it has been revealed the part-time model played a part in saving Australian lives in battle during the Vietnam War.

Stan Morley and Ms Butterworth were the best of mates growing up.

"Just that laugh — she was a great girl — I only have to see a picture of her or think of her and I can hear the laugh," he said.

Stan was from a military family and joined the army at 17, knowing he would be sent to Vietnam.

Lucille Butterworth vanished in 1969 and never knew how her gift helped save lives. ( Supplied )

Ms Butterworth gave him a chain with a tiny pocket knife on it when he joined.

There was a second gift of a lighter when he was training in New South Wales and, when on leave in Hobart before being sent on to Vietnam, a toy clicker.

"She said 'if you ever feel down or homesick or whatever just click it and it will jog you back into reality'," Mr Morley said.

But it became much more. Mr Morley believes it is the reason he and other members of his unit made it home at all.

Mr Morley was an army tracker and was sent ahead of the rest of his unit to act as a listening post for a planned ambush in late 1969.

"When I heard them coming there were too many of them — they were coming from all directions," he said.

To yell out a warning would have given his position away, but the noise of a clicker in the jungle was just enough to stand out and alert his comrades.

"We didn't lose anyone — I think there was a bullet hole through a barrel … that was it," he said.

Ms Butterworth had vanished from a Hobart bus stop a few months before, so she never knew how her gift had saved her friend's life.

"She would have saved a lot with those clickers," he said.

There'd be a lot of people that wouldn't be around … using a clicker you could tell where everyone was in the jungle because you can't see each other."

Stan Morely (L) presented Ms Butterworth's brother Jim with her gifts at Jim's 80th birthday. ( ABC News: Adam Harding )

It started a run on the toys, which Mr Morley said became known as Lucies or Lucy Clicks.

"I told Mum about it and she went into Coles and other places and bought clickers and sent them over and people started using them," he said.

"So after that we started using the clicker if we were in a firefight instead of saying 'is everyone right?'.

"Because you moved around a bit, people would click their clickers and you'd know where everyone was."

Historian Reg Watson said it was not the first time clickers had been used in war. American paratroopers used them in the D-day invasion in World War II.

"The concept was that when you land over a large area you've got to make contact with your comrades so they devised this plan — one click would mean 'I'm here' and two clicks would mean 'I hear you'," Mr Watson said.

The use of the clickers in D-day featured in the movie The Longest Day in 1962.

It starred many Hollywood greats including John Wayne and Richard Burton, and it is possible that inspired Ms Butterworth to give her friend a clicker to take to war.

Gifts returned to Lucille's brother

He no longer has the clicker but Mr Morley, who has a terminal illness, chose the 80th birthday of Ms Butterworth's brother Jim to present him with the chain and the lighter.

It was the first time the story of the Lucy Clickers had come to light.

"I think it's not only a wonderful aspect of the whole Vietnam story and Australia's participation," Mr Watson said.

"It adds a touch … almost a very profound human touch to the case of Lucille Butterworth."

Hidden inside the lighter were three gem stones Mr Morley bought for Ms Butterworth while on leave in Sydney, including her birthstone.

It was a gift he never had the opportunity to give her and one that he has carried with him for almost 50 years.

In May this year, Coroner Simon Cooper found convicted killer Geoffrey Charles Hunt had strangled Ms Butterworth shortly after picking her up from the bus stop in August 1969.

Hunt has consistently maintained his innocence.