As detectives take the extraordinary step of swabbing 600 men over the high-profile murder of Tracy Connelly in Melbourne, it is fitting to look back at the experience of a tiny town in NSW's cotton heartland that was, for a little while, big news.

Wee Waa (sounds like 'we-war') sits in the state's north, two-and-a-half hours inland from Tamworth.

In April 2000, the town touted as the birthplace of the country's modern cotton industry became the site of one of Australia's earliest mass DNA screenings.

And David Sweeney, Wee Waa's sole lawyer, was among one of the only voices of dissent.

There had been a horrific rape in 1999. In the early hours of New Year's Day, 91-year-old Rita Knight was violently assaulted in her home.

Mr Sweeney knew Miss Knight. She was a devout churchgoer and keen piano player. If you walked past the house she lived in alone – a block from the police station – you were likely to either hear her playing or see her sitting on her landing.

She was also as tough as nails, Mr Sweeney said, and after the attack she said her predator needed his "testicles on an ants mound".

"You should have heard her," he said.

Mr Sweeney also knew the rapist. But that would come later.

By April 2000, the investigation had stalled, so police asked the men of Wee Waa aged between 18 and 45 to volunteer a mouth swab to be tested against DNA left at the scene.

There had been a similar exercise undertaken in Western Australia in the 1990s,  but in the year 2000, mass screening was still new.

It created somewhat of a divide in Wee Waa, but most there saw the screening as worthwhile given its potential to solve the crime. Out of the 500 men who fit the broad profile, police said fewer than 20 refused.

"I didn't actually match the profile," Mr Sweeney said, "I wasn't even in the town on New Year's Eve, I was actually in Brisbane."

But even then, he was cautious about an unqualified acceptance of the mass DNA screening and spoke out against it.

"It wasn't an answer to say, 'I've got nothing to fear, I've got nothing to hide so why should I care about a DNA swab?' Everyone has a right to privacy," he said.

He remembers a local coming up to him – "You're an idiot! The whole town thinks you're an idiot!" – while he was talking to reporters who were in Wee Waa for the story.

He shrugged it off.

"I don't know, people might have bitched about me behind my back, but on the other hand, people crossed the road to congratulate me," he said.

Melbourne University professor Jeremy Gans, who has researched mass screens across the globe, said testing is most often a tactic to flush out targets.

"Most of the time they do these things because they've got their eye on people and it's the pressure," Dr Gans said.

It worked in Wee Waa. Ten days after providing a swab and before it could be processed, 44-year-old farm labourer Stephen James Boney walked into the local police station and confessed, saying he buckled to the inevitability of his capture.

"I knew the guy very well ... It came as a complete surprise that he was the person," Mr Sweeney said.

St Kilda isn't the same-sized fishbowl as Wee Waa and, while many knew sex worker Tracy Connelly (she was known for watching-out for the younger women on the beat), they are less likely to know her killer.

Ms Connelly, 40, was also attacked in the place she called home; a van she shared with long-term boyfriend Tony Melissovas. Mr Melissovas found her beaten body inside the white Ford Econovan in Greeves Street on July 21, 2013.

Police believe she may have been killed by a client in a robbery gone wrong.

The screening that has recently begun is aimed at testing the DNA of 600 men in what police say is the largest screening in Victoria's history.

The men asked for a swab may have been in the area at the time, or had been a client of Ms Connelly's. They could also be men who have had a history of violence against sex workers but have not offended so seriously that their DNA has been taken before.

The testing is unlikely to cause the same public angst as it did in Wee Waa. The men being sampled are more likely transient and laws in place in Victoria stipulate voluntary samples may only be used for that case and that case alone before being destroyed.

Sally Tonkin was the chief executive of the St Kilda Gatehouse, a haven for sex workers, at the time of Ms Connelly's murder.

"She's still very much talked about and remembered," Ms Tonkin said.

"We are so encouraged with the step that has been taken, that it's being pushed to this extent ... For the community, it's really concerning when someone's out there who's capable of this."

Mr Sweeney left Wee Waa four years after the screening to start his own firm. From his office in Sydney, Wee Waa is a fading memory.

"I had a great time there. The friends I made are friends for life, I raced around [as] a bushman when you're a city bloke," he said.

Would he refuse to hand over his DNA again?

"In that case, it was the loss of the presumption of innocence. You were presumed guilty," he said.

"Today, I'm not going to give an answer to that question. I don't think there is a right or wrong answer."

Anyone with information about the murder of Tracy Connelly can phone Crime Stoppers on 1800 333 000 or submit an online confidential report.