A pedophile school bus driver was extradited to Adelaide in 2002 only after pressure was put on police by the city's Catholic Archbishop Philip Wilson, a royal commission has heard.
The Adelaide Archdiocese even offered to fund the extradition, after a top police officer, because of budgetary constraints, rejected a 1998 application to extradite Brian Perkins from Queensland.
Perkins sexually abused intellectually disabled boys between 1986 and 1991.
In 2002 Detective Sergeant Leonid Mosheev was told there was a direction from the Police Commissioner to bring Perkins back, he testified to the commission on Wednesday.
This came about because of pressure from the Archbishop Wilson who had visited the police commissioner, he said.
Beliefs about problems associated with evidence from an intellectually disabled boy were also part of the reason for the decision not to pursue the extradition, Det Sgt Mosheev said.
He was giving evidence in Adelaide on Wednesday at the Royal Commission into Institutional Responses to Child Sexual Abuse.
"It was well known that quite often extraditions would not be approved even with serious matters," he said.
Detective Sergeant Gregory Ramm described the refusal to extradite Perkins as "pretty poor", saying Perkins was one of four men involved in a "pedophile network that stretched worldwide".
The commission is investigating Catholic St Ann's Special School in Adelaide and Perkins.
Det Sgt Mosheev went to Perkins' home on August 21, 1991, and seized two canisters of film, later found to contain photos of naked students.
Perkins fled the address but another investigation began after a journalist, in May 1993, provided police with a wooden box containing 33 roles of films, negatives and contact sheets.
"We had thousands of photographs and we identified about 12 children. But there were another 50 to 53 that we did not have a chance to identify," Det Sgt Ramm said.
Perkins and three other men were arrested in September 1993. But the then-assistant commissioner Colin Watkins, who has since died, told detective to stop the investigation.
Det Sgt Ramm said they were told to prepare their prosecution briefs on the evidence they already had and that was it.
"There was so much more that needed to be done, so many other victims and offenders that needed to be dealt with - it never happened," he said.
Perkins skipped bail in 1994 but in 1998 Det Sgt Ramm discovered he was living in Queensland after he renewed his licence.
Det Sgt Ramm said he attended a meeting with members of the church and parents in October 2001.
"It was expressed at the meeting that the Archdiocese would fund the costs of the extradition to make sure that he was brought back,' He said.
Perkins died in prison in 2009 after being jailed for 10 years in 2003 after pleading guilty to sex offences.
The hearing continues.