As the Queensland city of Mackay mourns the brutal stabbing death of 23-year-old Shandee Blackburn, police scour the Nerang River for any trace of mother of two Novy Chardon.

If she's been murdered then a killer is on the loose. If not and she's staged her own disappearance then this is one of the most intriguing missing persons cases in Queensland history.

Novy's husband John Chardon was the last person to have seen her alive.

More stories from Today Tonight

• Home invader nightmare
• Priest cops an earful
• Conman gets caught out

John runs a lubricant company and is now in Indonesia with his children and made it clear he is in no hurry to come back.

Former homicide detective Bob Munz believes whether investigators declare it or not, he is a suspect.

“In most murders of a woman who is married, you would have to ask questions of the husband. Even if it was just a background check, and of course you would need his alibi himself, and you would need to either eliminate him or put him down with others as a suspect,” he says.

Statistics show most murders are committed by someone known to the victim.

In Mackay right now emotions are high and leads on suspects are low.

“Even though you know an investigation often goes quiet and we don't hear much about what is going on, it might actually elevate the public’s fear because they think there is nothing being done,” Mr Petherick says.

If Shandee Blackburn's murder is random, the job of police will be that much harder.

Bob munz however believes the statistics don't lie and that shandee's killer isn't a complete stranger.

“I'd be thinking about previous relationships is there a suitor out there that has been discarded that is trying to get back to see her it would appear somebody has known that is the way she walks home.”

Over the weekend, police re-created Shandee’s final hours. And 10 days on they're still searching for clues.

Meanwhile at least one killer is still on the loose.