In some cases, vulnerable women, were groomed over Facebook by male officers. In other incidents the offenders used the force's internal database to access personal details to establish contact. The report, released on Wednesday, found family violence victims were the most common victims of predatory police officers in its examination of 142 allegations of predatory behaviour by Victoria Police over the past decade. It examined complaints ranging from sexually inappropriate comments or relationships, through to stalking and assault. Victoria Police Assistant Commissioner Luke Cornelius told radio station 3AW he was "deeply ashamed" that officers had been taking advantage of victims of crime, but said that that alone was not a sufficient response. "This demands more than mere shame, this demands a very clear call to action to address that small number of people - we believe - are preying on the community," Mr Cornelius said.

Among the most damning cases revealed in the IBAC report was a male officer who allegedly sexually assaulted an 18-year-old woman who had been arrested under the Mental Health Act. Days after taking her to a hospital for assessment, the IBAC report stated, the officer began contacting the woman through Facebook and an "intimate relationship" developed. A social worker helping the woman made a complaint to Victoria Police after she became aware of the relationship. While the officer was under investigation, another alleged victim came forward.

The second woman, a victim of family violence, complained that the officer had made inappropriate, flirtatious comments to her before making unsolicited attempts to contact her via Facebook. The officer was charged with disciplinary offences but resigned prior to the disciplinary hearing. Professional Standards Command investigators discovered another complaint made against the officer several years earlier where he had been accused of forming yet another inappropriate relationship with a family violence victim, the report found. Another case IBAC examined concerned a male officer who allegedly sexually assaulted a female victim of family violence whom he had met on-duty. A number of female police officers came forward during the internal investigation to state they too had been subjected to sexual harassment and assault by the officer.

Some had reported the conduct to their superiors, but no action was taken. The investigation identified the officer also frequently misused the Law Enforcement Assistance Program (LEAP) database to access personal details of women he met on-duty to pursue for sexual relationships. Some were vulnerable women with mental health issues or family violence victims. The officer was charged with disciplinary offences, but resigned. Criminal offences were not laid due to lack of evidence. The IBAC examination, which comes after a Fairfax Media report on Monday that revealed the issue for the first time, also found:

One-third of the alleged offenders were subject to two or more separate allegations.

Officers from rural locations are over-represented as alleged perpetrators of predatory behaviour.

Alleged predators commonly misused police databases to gain personal details of victims.

Perpetrators had on average 13 years of service at the time a complaint was made.

A number of these officers were still employed by Victoria Police at the time the IBAC report was drafted. The report stated the offences were committed by a small minority of officers, that nonetheless had a "devastating" impact and were under-reported. "Our research indicates that victims of predatory behaviour by police are some of the most vulnerable people in the community – such as victims of domestic and family violence or sexual assault, sex workers, or people with mental illness, or alcohol or drug dependency," IBAC Commissioner Stephen O'Bryan QC said. "Predatory behaviour by a small number of police officers can have devastating impacts on victims, while undermining the crucial work of the vast majority of their colleagues." The IBAC report was published ahead of a separate harassment and discrimination inquiry by Victorian Human Rights and Equal Opportunity Commission that is due to be released next week.

Fairfax Media reported on Monday that some of the issues discovered in this inquiry are "even worse" than had been found in the Australian Defence Force, according to sources close to the commission. Thousands of police officers have reported incidents of discrimination or harassment to the commission when they filled out a survey sent to them as part of the agency's inquiry. The commission's inquiry was set up by former commissioner Ken Lay, who also formed a police taskforce, Salas, to investigate officers for abusing or harassing colleagues. Salas is investigating about 35 cases, including one historical allegation of rape. The commission's Victoria Police report has some similar findings to the 2012 report by the national human rights commission into the Australian Defence Force