The researcher, Sally Muytjens, spent more than three years investigating "dark networks" of paedophile clergy in Victorian dioceses. She published the research late last year, receiving a doctorate from Queensland University of Technology. Muytjens’ research found the largest and most active dark networks were at schools including St Alipius in Ballarat and Salesian College, Rupertswood, and orphanages including St Vincent de Paul’s in South Melbourne and St Augustine’s in Geelong. One of the worst offenders, convicted paedophile and former Christian Brother Edward "Ted" Dowlan, was active in five of the 16 dark networks, she found. Loading Her study also identified Christian Brother Rex Francis Elmer as a member of two paedophile networks. The Sunday Age last week revealed that Elmer taught at Catholic schools in regional Victoria and Africa for decades after his order first knew he had abused children at a Melbourne orphanage.

In her thesis, Muytjens used a research method called social network analysis, which can reveal hidden patterns and ties between members of groups and provide insights into how they operate. Using SNA enabled her to identify connections between clergy perpetrators and specific locations in Victoria from 1939 until 2000, unearthing what she described as a pervasive “sexual underworld” that had the potential to destroy Victorian dioceses. Loading Elsewhere, SNA has been used to map links between terror cells involved in the September 11, 2001, attacks and 2005 London bombings, and to track child sex trafficking networks in Britain, Italian money-laundering rackets and an Australian amphetamine trafficking ring. It has also been employed to track the spread of contagious diseases, as well as population displacement after natural disasters.

Muytjens also drew on material from the Victorian parliamentary inquiry and the Commonwealth Royal Commission into Institutional Responses to Child Sex Abuse, victims’ advocacy group Broken Rites and media coverage of criminal trials involving clergy, to map links between clergy child sex abusers in Victoria over six decades. Her thesis examined the responses of the Catholic Church to such criminal activity, describing the institution as a "grey network" that repeatedly facilitated abuse. Loading “One of these patterns was promoting known clergy perpetrators of child sex abuse to senior positions which not only provided further access to victims but also placed them in positions where they were better able to protect the dark network from exposure,” she wrote.

The code of silence among Catholic clergy in Victoria mirrored patterns of behaviour exhibited by groups including crooked police and the Mafia, Muytjens added, and that “extended to a refusal to give evidence to the police". "Similar methods were utilised by clergy perpetrator networks within the Victorian Catholic Church to maintain silence.” Documented clusters of paedophile clergy, including at St Alipius Boys’ School in Ballarat in the 1970s, showed they were “conducting illicit activity in an organised and co-operative way”, Muytjens wrote. Dowlan and notorious paedophile priest Gerald Ridsdale both had multiple convictions for sexually abusing children, including at St Alipius. Another four clergymen were each part of least two different clusters of abusers at different times, Muytjens found. “Some [clergy] committed child sex abuse at institutions where they were the only known dark network actor … [but] they were also transferred to parishes where there were clusters of other known clergy perpetrators. “These perpetrators were part of multiple clusters at different times … As [Ridsdale and Dowlan] were prolific perpetrators, it can be reasonably argued that [they] were transferred out of clusters when subject to complaints of child sex abuse but were returned to clusters where they could be better supported and protected through stronger ties.

“Fr Ridsdale and Br Dowlan’s movement between clusters ... [and] the number of convictions for these two clergy perpetrators demonstrates the unfettered access they had to child victims.” The church’s pattern of response to complaints of child sex abuse by its clerics functioned as a resource for the paedophile rings, Muytjens found. “Members of the sexual underworld support one another in seeking positions of responsibility by praising one another and condemning any critics … this sexual underworld is so pervasive that acknowledging and addressing this may destroy a Diocese,” she wrote. Drawing on research from around the world into child sex abuse by Catholic clerics, she said the data showed that "clergy perpetrators ... were placed in roles of recruiting boys to the priesthood”. Loading

Muytjens’ thesis was completed around the same time as an investigation by The Age revealed that clusters of paedophile priests in Victoria worked together to sexually abuse children, including at Melbourne’s Corpus Christi seminary. Her research was supervised by UTQ School of Justice criminologists Dr Jodi Death and Associate Professor Mark Lauchs. Lauchs’ research has focused on organised crime and corruption, while Death has also mapped paedophile networks of Catholic clergy, including among the Christian Brothers in Western Australia. Associate Professor David Bright, a criminologist and clinical psychologist who has worked with convicted sex offenders, has used social network analysis extensively in his research, mainly in relation to drug trafficking and terrorism. He said SNA was an effective tool for displaying links between overlapping abusers in the church: "The clustering that Sally found, it’s quite persuasive in that what it's suggesting is that there were clusters of offenders in institutions and that this is the case more so in some than others. "It strikes me that either these individuals were incredibly good at manipulating the system to be at the same facility ... or the system was just so negligent about this and turned such a blind eye and was so convinced that these things weren’t going on that it just allowed it to continue."