Twenty Victorian domestic violence offenders had 10 or more victims. Now police are looking for other men who might have got away with similar serial offending. "We are looking at the high risk and extreme offenders that are moving through different relationships and many of those victims are not reporting it to police," Inspector Zervaas said. Detectives have found that the worst family violence offenders are often predatory, selecting vulnerable women with troubled backgrounds as victims, taskforce Detective Senior Sergeant Anthony Mercer said.

"We've found that their victims may have been in Department of Human Services care as a child, or may have not been able to finish school because of sexual assault," Detective Senior Sergeant Mercer said. "A lot of these key indicators are repeated. It may be that this perpetrator is just lucky enough to come across people who are almost exactly the same, but what we say is that they identify these factors, and select their partner based on them." In the taskforce's cases to date, detectives have been staggered to find that the number of suspected victims linked to an offender doubled as their investigation progressed. Those victims have reacted positively when contacted by taskforce detectives, despite some feeling as if they were let down by police when they reported violence in the past. "Some victims will say 'has he killed someone?'," Detective Senior Sergeant Mercer said.

"Or they'll say 'am I in danger, is he coming to get me?' or 'thank God you're here, I was waiting for someone to come and speak to me' or 'please don't tell me someone else has been offended against'. "The response we have got to date has not been one ounce of negativity, it's been more relief, or excitement. I'm not going to sit here and say that Victoria Police's response to them initially was perfect, but what we're able to provide them with now is an opportunity to tell their story, so that they do get their day in court if that's possible." Detective Senior Sergeant Mercer would not comment on how many cases were open, but confirmed there were investigations into offenders based in Melbourne and regional Victoria, including some who are in prison. Taskforce detectives have homed in on serial offenders suspected of committing crimes 20 years earlier, and tracked down victims who have moved interstate. The taskforce is based on a Scottish model praised internationally for revolutionising the policing of family violence by investigating domestic abuse with the same rigour and intensity as homicide. Scotland's taskforce exposed some of the most brutal family violence offenders the country has seen, such as Joseph Loughran, who abused five Glasgow women during an almost 30-year history of violence.

The development of a similar taskforce in Victoria showed police were still coming to grips with the extent of the carnage wrought by family violence, Detective Senior Sergeant Mercer said. Intelligence gathered since last March – when former chief commissioner Ken Lay established Australia's first family violence command headed by Assistant Commissioner Dean McWhirter – revealed the need for a specialist taskforce to support the 32 family violence teams and 32 Sexual Offences and Child Abuse Investigation Teams across Victoria. Aside from Inspector Zervaas and Detective Senior Sergeant Mercer, two detective sergeants and eight detective senior constables are on the taskforce. Last week, the state government unveiled a $10 million family violence victims advisory council, to be led by Rosie Batty, and the findings of the Royal Commission into Family Violence will be released on Tuesday.